The $399 Digital Decoding Engine is for real.

But how can Audio Alchemy make an outboard D/A converter for about half the price of the next most inexpensive decoders (the PS Audio DigiLink and Melior Bitstream D/A)? Can it be any good? These were my first reactions to the DDE, and I'm sure many of you are asking these same questions.

First, however, some background on the company: Audio Alchemy is the name of a new line of digital products manufactured by the California-based LM Acoustics. The company's other products include a Digital Transmission Interface ($299) that goes between a transport and processor, a two-piece CD transport ($699), the Clearstream digital coaxial cable ($49), and the Analog Decoding Engine ($199) that "conditions" the analog output from a D/A processor. Looking at their line, it is clear that Audio Alchemy is attempting to boldly go where no digital manufacturer has gone before—at least in price.

In addition to making the Audio Alchemy line, LM Acoustics designs and manufactures a variety of audio products for many companies. The Music and Sound DCC-1 that I reviewed in March, for example, was designed and built by LM Acoustics. The company is currently working on several other, more ambitious digital products.

Does the Digital Decoding Engine bring a new level of affordability to digital processors, or is it a toy that can't compete with established yet affordable performers like the PS Audio SuperLink and Meridian 203?

Let's find out.

Technical description
The Digital Decoding Engine (DDE) is so small and light that many people do a double take when they find out it's an outboard D/A converter. Easily held in the palm of the hand, the diminutive DDE isn't what we've come to expect D/A converters to look like.

Despite its small size and low price, the DDE has the features of the full-sized (and -priced) outboard decoders. Coaxial and optical inputs are provided (on RCA and Toslink jacks), with a front-panel selector switch. The front panel also includes an absolute polarity switch and three LEDs that indicate when the unit is locked to an incoming digital signal, and that the analog and digital power supplies are working.

The rear panel holds the previously mentioned RCA and Toslink input jacks, as well as a digital output for driving a DAT machine or future digital recorders having S/PDIF (Sony/Philips Digital Interface Format) digital inputs. Analog output is provided on two RCA jacks, which, like the digital input and output, are gold-plated. A mini-jack accepts ±12VDC from the outboard power supply, a 2" by 2½" by 1½" box.

An unusual feature of the DDE is the I²S Bus found on a rear-panel DIN connector. The I²S Bus (pronounced "I squared S") provides access to the raw serial 16-bit digital audio data after it has been decoded from the incoming S/PDIF delivered by a CD transport just before the D/A converter. This allows digital signal processors to be connected to the DDE while keeping the signal in the digital domain. The I²S Bus can be thought of as an expansion slot in a personal computer: both provide a communication path between the device and the outside world. At Audio Alchemy's CES booth, I saw a prototype Digital Signal Processing (DSP) box that connects to the DDE's I²S Bus and is controlled by a personal computer, providing a variety of signal-processing functions including equalization and reverberation enhancement. The I²S bus also allows the user to plug in a newer, upgraded D/A converter to the DDE without the expense of replacing the entire input and demodulator stage, chassis, and other hardware. Don't be surprised to see future products from Audio Alchemy that use the latest DACs, yet connect directly to the DDE.

Popping the Engine's hood revealed a compact, efficient topology and layout. Despite the extraordinarily low price, the DDE's designer didn't take a cheap-as-possible approach—several design touches adding to the unit's cost could very easily have been omitted.

The power supply, which consumes about 15% of the printed circuit board real estate, consists of four regulation stages: +8V and –8V stages supply the output op-amp, +5V supplies the input decoder and demodulator, and a second +5V regulation stage powers the Bitstream chip. Each stage is regulated by a three-pin regulator, and filtering is provided by two electrolytic caps, one 1000µF and one 470µF. This internal supply is driven by ±12V DC from the previously mentioned outboard unit, which contains a power transformer, two full-wave bridge rectifiers, and two 2200µF filter caps bypassed with 0.01µF caps. The choice of a 12V output from the power supply is deliberate in order to allow the DDE to be used in car stereo applications.

The chip set is the Philips SAA7274 S/PDIF receiver and decoder coupled with Philips's SAA7323 Bitstream DAC/filter chip. The S/PDIF receiver circuit is unusual in that a Voltage Controlled Oscillator (VCO) supplies the reference Phase Lock Loop (PLL) frequency rather than the ubiquitous crystal clock generator. An additional chip next to the 7274 gets a reference voltage from the 7274 and outputs a frequency back to the decoder chip. This circuit's job is to recover the clock imbedded in the incoming S/PDIF signal. This technique reportedly results in lower clock jitter than standard PLL implementations (several hundred picoseconds rather than 2–5 nanoseconds). In addition, the DDE will lock to any incoming sampling frequency between 40kHz and 50kHz, but won't accept the 32kHz sampling frequency used in DAT's extended play mode and Direct Broadcast Satellite (DBS). This circuit is a good example of my impression that the DDE wasn't built strictly on price; the VCO technique added more parts and design time to the DDE, yet wasn't essential to its operation.

The 7323 Bitstream chip incorporates the digital filter, Bitstream DAC, and analog output stage. Audio Alchemy has chosen to bypass one of the 7323's analog stages in favor of a single Analog Devices AD746JN dual bi-FET op-amp, shared between left and right channels. (The first op-amp in the 7323 is part of the switched capacitor network and can't be bypassed.) Again, replacing the 7323's internal op-amp with the moderately expensive AD746JN reflects the attempt to make the DDE sonically competitive, not just price-competitive.

Output muting is accomplished by tying the front-panel lock indicator to the Bitstream chip, muting the output until the unit has locked to the incoming digital signal. De-emphasis is performed by the 7323 Bitstream chip in the analog domain with an internal resistor/capacitor pair.

All resistors are metal-film types, and capacitors are polystyrene and polypropylene. The very simple design is executed with a minimum of parts. Although I was surprised to learn that a company could build and sell a $400 D/A converter (especially an American-made product sold through normal retail channels), I was even more surprised after looking inside the Digital Decoding Engine. Despite its simplicity and economy of construction, it nevertheless looks like it should retail for more than $399. According to Audio Alchemy President Mark Schifter, the DDE's retail price is in line with standard industry pricing based on parts cost. The low actual profit (as opposed to profit percentage) is reportedly made up for by selling a lot of units.

Listening
My first impression upon hearing the Engine? Competent—even surprising—but not outstanding in relation to more expensive processors like the Meridian 203 and PS Audio SuperLink. Considering, however, that the DDE costs not even two and a half times less than the next cheapest processor to which it was compared, its performance was very impressive.

What the DDE gives you that is often missing from cheap CD players is detail, transparency, and clarity. In this regard, the DDE has more in common with the good outboard decoders than with low-priced CD players. Through the DDE, there wasn't the opaqueness and detail-obscuring haze overlaying the music so often heard from inexpensive digital playback. The music had a vibrant immediacy and palpability rather than a congested, lifeless character. In addition, instrumental outlines were clearly defined, creating the impression of individual instruments in the soundstage. Many high-priced decoders don't do this well in delineating image outlines, an important factor in rendering the illusion of musicians in the listening room.

Compared with the Meridian 203, the DDE had a more sharply focused rendering and greater resolution of instrumental outlines. The 203, however, offered a greater sense of the instruments being surrounded by air and space. This was more apparent on naturally miked recordings, giving the 203 a clear edge on classical music and most jazz. Through the DDE, the soundstage was vivid and sharply defined, but lacked the impression of instruments floating on air between the loudspeakers. Herbie Hancock's piano on the excellent Jack DeJohnette album Parallel Realities (MCA MCAD-42313, Vol.13 No.9) had less air surrounding it and appeared more forward in the soundstage with the DDE than through the 203 (footnote 1).

In addition, the illusion of space and soundstage depth was easily superior through the 203. I felt the DDE's presentation was too forward and lacking an ultimate feeling of size and space. The 203 threw a much more accurate rendering of hall acoustics and space. Julianne Baird, for example, on The English Lute Song (Dorian DOR-90109), was farther forward in the presentation, drier, and less enveloped in the gorgeous acoustic of the Troy Savings Bank Music Hall when reproduced by the DDE. However, the distinction between lute and voice was greater through the DDE. The Stereophile recording of Brahms's Piano Sonata in f, from the Intermezzo CD (STPH003-2) was particularly revealing of the DDE's limitations in reproducing space. The DDE made the room seem much smaller and didn't reveal the wealth of natural ambience on this recording. Through the 203, the soundstage suddenly expanded, with room reflections becoming clearly audible at the soundstage's edges.

Similarly, the DDE had a more forward rendering than the 203, but less resolution of inner detail and finely woven textures. The DDE seemed to present all its detail right up front, rather than in layers and layers of subtle gradations. In this regard, the 203's presentation was more relaxed, interesting, and musically involving. I preferred listening into the music to hear inner detail and nuance, rather than having lots of detail thrust forward. The DDE's forward and highly detailed character tended to make long listening sessions fatiguing. In short, the DDE's presentation of musical information was somewhat blunt and aggressive, the 203's refined and gentle.

One area where the DDE clearly bested the 203 was in conveying the energy and rhythmic drive of music. The DDE's bottom end had a punch and solidity that was particularly satisfying. In addition, there was a greater feeling of what Martin Colloms aptly describes as "pace." I found myself tapping my foot quite often when listening to the DDE, always a good sign. This is perhaps the result of the DDE's fuller, weightier bass presentation, something that made bass guitar lines seem to bounce more with the rhythm. Contributing to this impression was the DDE's more dynamic character. Snare and bass drum seemed more dynamic and punchy, adding to the feeling of drive and energy. Neither processor, however, was a match for the SuperLink in either dynamics or bass drive. I've yet to hear a 1-bit converter approach the bass tightness, authority, and dynamics of a good multi-bit–based processor, especially the outstanding SuperLink.

My main complaint about the DDE was the treble. It tended to be forward and hard, especially during peaks of high recorded signal levels. Cymbals were more prominent in the presentation than is natural, and the upper harmonics of high-frequency–rich instruments were overly emphasized. The delicacy and air in cymbals heard through the 203 were missing from the DDE's rendering. I've found that many 1-bit decoders tend to get hard as signal level increases; the DDE was no exception. Snare drum, with its high peak level and substantial high-frequency component, was particularly edgy. The snare-drum dynamics just mentioned were perhaps more the result of this hardness than of actual dynamic contrast; brittleness and edge give the impression of greater volume.

Instrumental textures, while detailed and vibrant, tended to be a little synthetic sounding. There wasn't that lush liquidity and warmth that conveys an instrument's true tonal shadings. Listen to Joe Henderson's unaccompanied sax that begins "Ask Me Now," from McCoy Tyner's new Chesky CD (New York Reunion, JD51). Through the DDE, it was somewhat sterile, lacking warmth and body in the midrange, and a little edgy. By contrast, the 203 presented a much more believable rendering, with roundness, breath, and liquidity. The SuperLink also bested the DDE in ability to present natural timbres. In this regard, the DDE clearly sounded "digital" rather than more closely emulating good analog.

In remembering my experience with the identically priced Rotel RCD-855 CD player, I feel the DDE to be more detailed, and to have sharper soundstage focus and a more forward and vivid presentation than this popular CD player. The 855, however, was more laid-back, less fatiguing, and had better soundstage depth. Despite these factors, I would have to chose the DDE for its transparency, clarity, and soundstage delineation.

Conclusion
On the credit side of the ledger, the DDE is remarkably transparent, with a surprisingly well-focused soundstage. The DDE didn't homogenize instrumental outlines, a trait so common in inexpensive digital playback. In addition, this diminutive unit had good bass drive and ability to convey the music's rhythm. Finally, the DDE had lots of detail; I never felt I was missing a large part of the music, another characteristic of low-priced CD players.

On the debit side, I found the treble a bit hashy and forward, lacking the delicacy and nuance heard through the Meridian 203. Although the DDE's soundstage was superbly defined laterally, it lacked the sense of depth and ability to surround instruments with the recorded acoustic. This gave the entire presentation a forward immediacy that could become fatiguing after a long session. In addition, instrumental textures were somewhat synthetic and lacking the liquidity and roundness heard through other (admittedly more expensive) processors.

Overall, I preferred the Meridian 203 on classical music and most acoustic jazz. With some electronic music in which soundstage depth and accurate tonal shadings are less important, the DDE, with its superior rhythmic drive and sharper soundstage focus, ran a much closer race. I should reiterate that not only is the Meridian 203 two and a half times the DDE's price, it is, in my opinion, the best of the $1000 processors.

For music lovers on a budget, I can't recommend the Audio Alchemy Digital Decoding Engine more highly. While it has some sonic shortcomings, it nevertheless offers a level of musical performance previously unheard of at this low price. In addition, it is well made, incorporates most of the bigger units' features, has a five-year warranty, and is upgradable through the I²S bus when newer DACs become available.

For $399, therefore, the Audio Alchemy Digital Decoding Engine is a bargain. It's no giant-killer, but if you own an inexpensive CD player with a digital output and have been wanting to upgrade to an outboard processor, the DDE might be just the ticket.

That was a long time ago. I'm sure that, by now, we can all forgive Sony for using the LP as a yardstick against which to measure an improved version of a format that, in 1983, they had said was already perfect. (Really. It's okay. Time to let go.) Besides, from the moment I heard the SACD at that press event, I was indeed impressed by its analog-like sense of musical flow and momentum. So impressed that I purchased, within months of the format's introduction, one of Sony's SACD players—which, at the time, were not exactly cheap (footnote 1).

A lot has happened since then. Just as significantly, a lot hasn't happened since then—namely the acceptance, by more than an insignificant sliver of the market, of SACD hardware and software. Yet DSD is getting another shot at consumer acceptance: Witness the recent promotion of DSD music files on the one hand, and of USB-input DSD processors on the other. My friends, DSD streaming has arrived—and so, too, has the DA-06 digital-to-analog converter ($4990), from Japan's 89-year-old Luxman Corporation.

Description
But there's more to this product than just one compelling if slow-to-mature format. While the Luxman DA-06 is one of about three dozen converters on the market that can process and stream 2.8224MHz and 5.6448MHz DSD files, it also supports, via its USB input, PCM with word lengths of up to 32 bits and sampling frequencies of up to 384kHz. (Its S/PDIF, AES/EBU, and optical inputs support up to 24 bits and 192kHz.) Additionally, PCM playback through the Luxman DA-06 can be optimized with a choice of three user-selectable digital filters, derived from different 32-bit interpolation functions. (Users can just as easily select between two different high-frequency-rolloff characteristics during DSD playback, but those filters exist only in the analog domain.)

At the heart of all this flexibility is the Burr-Brown PCM 1792A 32-bit converter chip, which also appears in Luxman's D-06 SACD/CD player. According to Luxman, digital inputs of 44.1, 88.2, and 176.4kHz are upsampled by this converter to 352.8kHz, while inputs of 48kHz and its mathematically related frequencies are upsampled to 384kHz. Digital signals arriving through the USB input are said to be streamed asynchronously.

Useful controls abound, and I was pleased to see that Luxman has put them all on the DA-06's nicely styled front panel—and dispensed altogether with a remote-control handset, which I persist in regarding as the devil's plaything. A knurled, six-position rotary switch at the far right of the front panel selects among the various digital inputs—two optical, two coaxial, one AES/EBU, one USB—and a pushbutton toggle to its left can be used to disable the DA-06's digital output, in an effort to enhance analog-output quality. Still farther to the left is a notably clear, seven-segment LED display for sampling rates and word lengths (the latter functioning only with S/PDIF inputs); an adjacent pushbutton offers four levels of display brightness—or, for you empty-glass types, darkness.

At the far left of the front panel, a simple, two-position pushbutton is the sole means of turning the DA-06 on and off—another blessing to the user who sees little point in paying for the complexity of on/off/standby switching, and who prefers knowing, without ambiguity, when "Off" means off. Beyond that, the Luxman's four remaining pushbuttons were those I found most useful: controls for inverting absolute signal phase, selecting the digital PCM filter, and selecting the analog DSD filter, plus an Enter switch, which enables the user's choice in all three functions.

The DA-06's rear panel is straightforward. Single-ended analog output signals appear on a pair of RCA jacks, balanced signals on a pair of XLR sockets (pin 2 is hot). Two RCA jacks, two TosLink jacks, a USB Type B socket, and an XLR socket accept digital inputs of various types, and digital output is available from an RCA or a TosLink jack.

The DA-06's case consists of a hefty, well-finished steel bottom plate to which various thinner steel plates—for both structure and shielding—and the alloy front panel are bolted. A thin steel sleeve, finished in textured paint, covers the works: nicely executed, if a slight notch below what I would expect in a $5000 product. Interior build quality is superb, with most of the circuitry divided among three main boards, for analog output (the largest board), digital processing, and the power supply. Parts quality is good insofar as I can tell, with Luxman's own bespoke capacitors in many positions, and an especially beautiful, copper-wrapped mains transformer at the power supply's electrical heart.

Installation and setup
Being not too big, too heavy, or possessed of controls too inscrutable, the Luxman DA-06 was cake to install. My Apple iMac recognized it the moment they called to one another across a 2m-long WireWorld Revision USB cable—the processor appeared in the computer's System Preferences/Sound window as "Luxman DA-06"—and has never failed to do so in the days since, with no need for rebooting computer or processor.

As for playback software: I normally rely on Stephen Booth's very cost-effective Decibel (v.1.2.11) for all music files, and on Apple iTunes for streaming FM broadcasts, but at the time of writing neither program supported DSD. I deferred to the DSD enthusiasts among my colleagues and friends, who all pointed me toward Audirvana Plus ($74), v.1.5.12 of which has now imprinted itself on the magnetic dust of my hard drive (which is not quite the same as saying "I own it," but please humor me and play along). I suffered, early in the review, some concern that either Audirvana Plus or the Luxman DAC did not support MP3 files, as I was unable to stream music from my favorite Internet radio station; as it turned out, my first attempt at doing so came during one of WCKR's experimental-music hours—I had chanced on a period of extended silence written into a score. Subsequent broadcasts sounded fine.

Except where indicated otherwise, all of the following observations apply to the Luxman DA-06 with its two adjustable filters in their normal settings: P-1 for PCM [see the "Measurements" sidebar—Ed.], D-1 for DSD.

Listening
Reality prevails. And while I'm sure there exist hardcore enthusiasts who acquire every DSD file that's commercially available, and who make those files the predominant if not exclusive medium for all of their listening sessions, the digital-music "collections" of most audio enthusiasts are overwhelmingly dominated by PCM recordings: In the field, those are what most Luxman DA-06 converters will spend most of their time converting.

Consequently, although I laid in a good selection of DSD files chosen specifically for this review, I spent most of my reviewing time using the Luxman DA-06 for everyday listening: mostly 16-bit/44.1kHz PCM files, with a smattering of 24/96 and 24/192 PCM files. Used in that manner, the Luxman suggested an idealized and vastly more flexible version of the affordable and consistently listenable Halide DAC HD, which has become my USB reference during the past year. The Luxman went well beyond the Halide by sounding generously explicit, providing musical and sonic details in abundance and presenting them in a soundfield notable for its openness and general lack of murk. Still, the DA-06 had good substance, with a tonal character that was slightly—almost imperceptibly—warm and round, even with that default filter.

Before turning to the answers to those questions, let me tell you a tale. A friend of mine back in the UK finally gave into temptation a couple of years back and bought a Ferrari. It wasn't new, of course, but it was a beautiful car, Pininfarina-designed; I suppose you could call it a two-door sedan, to distinguish it from the hairier mid-engined Maranello machines. A year or so back, when I was visiting the old country, my friend was taking my wife and I for a spin in his dream car and asked if I would like to take a turn behind the wheel of the beast.

Would I? What would you have said?

Actually, I felt equivocal: bending the bodywork of one's friend's Ferrari is a surefire way of terminating that friendship! But drive it I did. Yes, you could buy a lot of Hyundai Excels for the price of such a car, even quite a few Mustangs. And an Excel will certainly get you to the same place via the same roads as will a Ferrari. But I am here to say that it is not the same experience. You may drive ordinary cars; with a thoroughbred like that Ferrari, driver and car take on a symbiotic relationship, the tires becoming the extension of your nerve endings. The car both is responsive to your wishes and feeds back all you need to know about the road and your relationship with it; it is almost as if you need only think about what line you want the car to take, and the deed is done (footnote 1). That Ferrari redefined my attitude to driving. No, I will never be able to afford one myself, but I am glad to know that it exists.

The only possible justification for high price, therefore, is that you get more, not only than you expected but also than you knew existed. That is the only standard by which to judge human artifacts designed without compromise, and it was only with that finally clear in my mind that I addressed myself to the subject of this review.

Technical highlights
The Accuphase DP-80L CD player and DC-81L digital processor are refined versions of the original DP-80 and DC-81 that I reviewed for Stereophile in Vol.10 No.6. That $8000 player featured a 2x-oversampling digital filter and discrete 16-bit DACs and had what was then the most accessible CD sound that I had heard. Even that well-known digiphobe Larry Archibald was moved to praise its sound. It didn't quite approach the resolving power of the original Stax Quattro, however, which was, in those far-off days—September 1987—the champ when it came to the retrieval of detail.

Identically styled and sized to the original '80/'81 combination, with champagne-gold front panels and highly lacquered persimmon wood endcheeks, the new units are very different under the skin. The player is based on a diecast aluminum chassis and now has a sprung transport, compared with the original's unsprung unit, and is capable of playing 3" discs. A hinged panel conceals all function buttons, apart from Play, Track Search (Back/Forward), and Pause. All the functions, including Open/Close, are duplicated on the supplied infrared remote control. The power supply is hefty, based on a large toroidal transformer at the unit's rear, and includes a line filter on the mains input.

A single large printed circuit board carries all the circuitry responsible for controlling the disc motor and linear-drive laser sled, for extracting and demodulating the data from the disc, and for presenting it in the EIA-standard, multiplexed, two-channel serial format to the output sockets. (Two optical outputs are provided, as well as a 75 ohm coaxial output.) Sony LSIs handle the servo control and digital processing tasks, and two 8-bit microprocessors are used, one each for mechanism control and for display/control key handling, with a single master clock used throughout the player. A discrete red LED numeric display indicates play, track/index number, and time, though, as with the display on the processor unit, this is a little too discreet, being hard to read from the other side of a sunlit room.

The equally massive DC-81L features separate toroidal transformers for the digital and analog sections, again with intrinsic mains supply filtering. A hinged flap on the front panel conceals digital source select and level up/down buttons, these duplicated on the DP-80L's remote control. Red LEDs display which of the optical or coaxial inputs has been selected, the sampling frequency of the input signal, whether or not the input is pre-emphasized, and the amount of output attenuation selected, in dB down to –40dB. Four main printed circuit boards, in two layers, almost completely fill the unit's interior. On the bottom are the digital and power-supply boards, the latter carrying the rectification and filter circuitry to provide separate regulated 5V rails for the digital circuitry and left and right DACs; left and right regulated –37V rails for the DACs; independent regulated ±19V supplies for the left and right analog boards; and a 24V rail for the relays.

A block diagram of the processor reveals that the digital board takes the input datastream, identifies the sampling frequency, and automatically reconstitutes the correct clock frequency—32, 44.1, or 48kHz—using a phase-locked loop. Error correction is applied if necessary, and the data for left and right channels are separated and resampled by a digital filter operating at 352.8kHz. This is specified as giving 110dB attenuation between 24kHz and 328.7kHz, with less than 0.0001% ripple in the passband. The digital filter also applies the appropriate de-emphasis (with an accuracy said to be ±0.001dB!) and adjusts the output level digitally. (This is done by multiplying the digital word representing the analog sample value by a coefficient selected by the volume up/down buttons. For example, to reduce the level by 20dB, each digital word would be multiplied by the coefficient 0.1.)

Whenever mathematical operations are carried out in the digital domain, the result is always a digital word with more bits than the original. This therefore has to be truncated somehow, and as simply chopping off the extra least significant bits reintroduces quantization noise, this must be done with some sophistication, rounding off rather than rounding up or down. The Accuphase therefore uses a noise-shaper circuit to accomplish this task, truncating the filter's internal words to 20 bits. The final stage on the digital board consists of two arrays of serial-to-parallel converters; the two sets of 20-bit-wide parallel datastreams, together with a "deglitch" signal per channel, are then taken via an edge connector to a mother board.

This, in turn, leads to the two analog boards, one per channel. These are shielded magnetically and electrically and each is also electrically isolated from the digital-processing board by 21 optoisolators—expensive, high-speed Hewlett-Packard devices—one for each bit and one for the deglitch signal. Finally, we get to the heart of the system, the D/A converter which, as in the original DC-81, is a discrete current-multiplying device. The '81L's DAC, however, is a 20-bit device, which implies a resistor tolerance of an astonishing less-than-one-part-in 2¹⁹; ie, less than 0.00019% error! This, I suspect, is where a significant proportion of the DC-81L's cost lies—and how do you even measure that you have trimmed a resistor to that degree of accuracy unless you already have an accurate 20-bit A/D converter?

The deglitch signal controls a sample-and-hold circuit, followed by a current-to-voltage converter. The analog output voltage is then processed by an 18dB/octave Butterworth low-pass filter to rid it of the 352.8kHz sampling frequency components and their multiples, this based on a GIC (General Impedance Converter) circuit; separate unity-gain buffers, constructed from discrete transistors, provide balanced and unbalanced outputs from XLR and RCA sockets respectively. No DC-blocking capacitors are used, the output buffers featuring DC-servo circuitry.

All things considered, the Accuphase player is built to an outrageously high standard and will probably outlast its owner, as indeed it should at this price level.

The Sound
So, what was the Accuphase combination's sound like?

In a word, superb.

"Superb," along with "excellent,""good," and "wonderful," is, as I tell other writers for this magazine when I'm wearing my editor's hat, a word conveying almost no meaning. I should expand on this adjective, therefore.

Tonally, the Accuphase is less thin than the sample of the Theta DS Pre that I auditioned, even taking into account the latter's de-emphasis error. It is slightly more forward than the Sony DAS-R1, however, with which it shares an awesomely deep bass, even with subwooferless Celestion SL700s. By comparison, the CAL Tempest II, while true to the musical aspects, is rather unsubtle in the upper midrange and altogether more untidy in its rendering of orchestral tone colors.

The V90 components turn all this around. They are tiny. Inexpensive. Beautifully built.

Your friends will laugh when you turn on your DAC. Or phono preamp. Or Bluetooth receiver (the V90 series now includes the V90-BLU). But, of course, audiophiles must forgo the pleasures of Bluetooth. Too easy. Too simple. Too much free music from thousands of sources around the globe.

I've been enjoying the V models since Musical Fidelity's founder and CEO, Antony Michaelson, introduced them four years ago. The V-DAC II and V-CAN II headphone amplifier have been references.

So when Antony introduced the third generation of V components, he gave me a bell, as they say in London. Which would I like to review?

All of them.

From V to V90
The V series has taken a 90° turn—a V-Tilt, if you like. The V90s are the third wave of Antony's mini-marvels that does not include a V-Tilt. No point in telling you what a V-Tilt was, since the long-ago-promised product never materialized.

Instead of slim and deep, the V90 components are 6.6" (170mm) wide by 4" (102mm) deep. This allows more space for connectors, switches, and knobs, as appropriate. The height remains 1.8" (47mm), and each V90 model averages about 1.3 lbs (600gm), not counting the new wall-wart power supplies that no longer hog two electrical outlets. Inspired by Steve Jobs or the Beatles, Antony packages the V90s in attractive white boxes. Dealers can dangle them from display hooks near the cash register. Small-box retailers!

Made in Taiwan, the V90 components are designed in England, especially for Alistair, Clive, and Nigel—you know, for chaps whose wives dole out their allowances. Sneak them into the house. Hide them behind your proper gear or some liquor bottles.

Antony cautions customers not to open a V90's case: there are no "user-serviceable" parts inside, and "tampering" will invalidate the warranty. "If customers did open the boxes, they would see mostly air there," he told me. "We use surface-mounted components for better reliability and short signal paths." Something like that. My tape recorder is busted.

"Then why buy your more expensive stuff?" I asked.

The industry's trend is to bloat the size and boost the price, but Antony takes the opposite tack. Of course, he makes more expensive DACs, headphone amps, phono preamps, the like. The idea of the V90 series is to approach those models' performance at a fraction of the size and a mere slice of the price.

The Musical Fidelity V90-DAC replaces the venerable V-DAC II, a sample of which has been part of my living-room system for two years. The V-DAC II is a very fine DAC. If you own one, maybe you don't need to upgrade.

The V90-DAC uses Burr-Brown's 32-bit PCM1795 chip. A two-channel sample-rate converter supports word lengths up to 24 bits and upsamples at 192kHz. A Texas Instruments streaming controller handles up to 24-bit/96kHz asynchronous via USB. The V90-DAC has not joined "the DSD Movement."

"Well, that would mean a separate DAC and a higher price," Antony replied by phone. Of course, he's planning to offer a DSD-capable DAC, but it won't cost $299, like the V90-DAC. There's a price for joining any movement.

Meanwhile, over the holidays, my kids bestowed on me four boxes of classical recordings comprising a total of 237 "Red Book" CDs. $25 digital downloads? I'm busy for a while. The Artur Rubinstein box alone contains 142 CDs and a hardcover book; the kids grabbed it for $96. That's 68¢ a disc.

On the V90-DAC's rear panel are RCA analog outputs, a USB input, and three S/PDIF outputs: one coaxial and two optical TosLink. The coaxial input operates at sample rates up to 192kHz, the optical and USB up to 96kHz, all with 24-bit word length. If you have a Bluetooth receiver with digital output(s), you can bypass its "native" DAC and run the signal through the V90-DAC, as I did with Musical Fidelity's V90-BLU and Arcam's rBlink. I used Musical Fidelity's M1CDT transport for spinning silver devils.

My head is spinning. I haven't even opened the 23-CD Leon Fleisher box. Compared to the V-DAC II, the V90 DAC offers still greater low-level resolution, superior dynamics, and fatigue-free listening. It does space and place particularly well, and really shines with brass, where lesser DACs tend to turn dull. The Brass Ear would love it.

An awful lot has changed since then, including, in recent years, a shift of PS Audio's emphasis from audio amplification to AC-power regeneration. Even more recently, under the direction of co-founder and CEO Paul McGowan, the company has added to its line a series of digital-to-analog converters, culminating in their new flagship, the PerfectWave DirectStream DAC ($5995.95). The DirectStream is notable for converting any and all incoming datastreams to DSD—which, in case you haven't been paying attention, is hot. Again.

Description
The DirectStream DAC has its origins in a 2011 visit by former Microsoft engineer Ted Smith to the Colorado mastering studio of digital-audio pioneer Gus Skinas. Smith was already a DSD convert, he told me—"The first time I heard an SACD, I went out and bought a Sony SCD-777 right away, which was unusual because I'd never before spent that much money on an audio product!"— and he brought with him a laptop full of music files and a D/A converter he'd just designed and built that decoded pure, single-bit DSD.

Skinas was so impressed that he got on the phone to his friend Paul McGowan and said, in essence, Get over here on the double.

McGowan went straight to Skinas's place and was, as he puts it, knocked out by the sound of Smith's prototype: "Ted was playing his laptop through a TosLink-to-USB converter. With a wall wart. And it still sounded amazing." A visit to the PS Audio factory ensued—Smith says he was impressed by the lack of a not-invented-here attitude among PSA's engineers—and an arrangement was made for Smith to design the company's first DSD processor, with final voicing to be done by McGowan and Arnie Nudell, the latter of Infinity and Genesis fame. The first samples of the PerfectWave DirectStream DAC shipped at the end of April 2014.

Aside from an XMOS chip used as an asynchronous USB receiver, the DirectStream contains no off-the-shelf chipsets: all of its code is written by hand into a field-programmable gate array (FPGA). In Ted Smith's conversion system, all input data—regardless of format, regardless of native sampling rate—are synchronously upsampled to a 30-bit word length running at 28.224MHz, which is 10 times the standard sampling rate for DSD. The next stage is a 5x downsampler, which brings the signal back down to 5.6448MHz, or twice the DSD rate. There follows a digital volume control: this operates on the incoming 30-bit PCM with 20-bit coefficients, meaning that the datastream after the volume control is 50 bits wide. A extra "top bit" is added, to eliminate any possibility of overload, then the 51-bit PCM data are converted by a sigma-delta modulator to single-bit DSD, still running at twice the standard sampling rate: "It's double because we need another octave to deal with the rolloff at the output stage," according to Smith. That final stage is based on high-speed video amplifiers and a custom-wound output transformer.

Smith says that while good power-supply design and careful parts selection played significant roles in maximizing the sound quality of his design, equally critical was a careful, comprehensive approach to eliminating all sources of jitter from the data flow. "Only anti-jitter techniques that work in real time are going to work in audio," he says, "and you need to apply them all, even if one technique, on its own, doesn't seem to have a huge effect. For example, you need a single, high-quality clock, and you don't want to run it through a digital multiplexer: Not knowing when something is going to happen—that actually is jitter. You also need to use RF cables instead of ribbon cables: RF cables have cleaner edges, and cleaner edges are less jitter!"

The DirectStream's cast-alloy casework—which proved impenetrable by all of the reasonable, nondestructive means at my disposal—is finished in a nice-looking textured paint, and the top is fitted with a sheet of glossy, piano-black MDF that may function as a mechanical damper of sorts. In addition to a small rocker Power switch and a slot for an SD card—I'll return to the latter in a moment—the rear panel is home to a selection of digital inputs: XLR (AES/EBU), RCA (S/PDIF), TosLink (S/PDIF), USB, and two I2S inputs using HDMI sockets—the last can handle DoP (DSD over PCM) or single- or double-rate DSD. The outputs provided are RCA (single-ended) and XLR (balanced). The level for the line signal appearing on both sets of output jacks can be set for low or high ranges, the latter suggested as appropriate for those who wish to bypass their preamplifier and directly drive their power amp(s).

Apart from a small indicator light, the DirectStream's clean-looking front panel has only an illuminated PS Audio logo and a 4" by 2.5" display—yet there was more to both than met the eye (or, at least, my eye): The logo is actually a soft-touch switch that toggles the powered-up DAC in and out of standby mode, while the display is a touchscreen from which the user can select (and give names to) source inputs, adjust volume, select output-level range, adjust screen brightness, and toggle between correct and inverted output-signal polarities. All of the display's functions are also accessible from the slender plastic remote handset (included).

Installation and setup
I removed the DirectStream from its very good packing, placed it in my system, and flipped its Power switch. The touchscreen informed me that the unit was Initializing. Precisely 11 seconds later, that message was replaced with the unit's clear and uncluttered default screen, which displays a volume scale near the bottom, a generously sized input-source indicator at the center, and other bits of data—plus two rows of dashes waiting to be replaced by numbers that would indicate the incoming signal's sampling rate and word length.

With the initialized DirectStream connected to my Apple iMac via a 1.5m WireWorld Revelation 2.0 USB cable, the correct device name appeared in the Sound subsection of my iMac's System Preferences window: "PS Audio USB 2.0 Audio Out." I assumed that all was well, but when I fired up my copy of the DSD-friendly Audirvana Plus playback software (v.1.5.12) and clicked on a song, my system remained resolutely silent—and no incoming data showed up on the screen.

It's not surprising, then, that many audiophile digital-to-analog converters come to us from the pro-audio industry, which has a hierarchy similar to the consumer side: value-oriented products all the way up to ultimate-performance brands. Examples of pro-audio companies that also offer audiophile DACs for consumers abound: Benchmark, CEntrance, Grace Design, Korg, Mytek, and Nagra, to name a few.

Igor Levin's Aardvark Audio began offering digital clocks and converters for recording studios in 1990, and quickly became known for its AardSync external clock. Aardvark eventually closed, and Levin opened Antelope Audio in 2005, making his mark in recording studios with the Isochrone digital clock and, later, a line of premium A/D and D/A converters. Antelope made a splash on the consumer side in 2012 with the Rubicon Atomic A/D–D/A preamplifier ($40,000), which, with its exotic rubidium atomic clock and over-the-top, Metropolis-style design, looks as if it had stepped out of a classic sci-fi film.

With the Rubicon, Levin and company were clearly making statements in both electronic design and aesthetics, but with their Zodiac line of DACs they were also distilling their technology into more affordable, no-nonsense products. Antelope's Zodiac Gold 384kHz DAC, which was supposed to be future-proof, turned out not to be when it came to DSD. Thus was born the Zodiac Platinum. For this review, Antelope shipped me a Zodiac Platinum DSD DAC in a bundle that included the second generation of their Voltikus power supply. The Platinum functions as a DAC, a headphone amplifier, and a preamplifier with analog and digital inputs.

The Zodiac Platinum is as complete as a $5771.15 (footnote 1) DAC can be in 2014, accepting any PCM format now commercially available and some that generally aren't (eg, 384kHz)—as well as DSD 64 and 128 via USB (DoP), which it upsamples to DSD 256. Antelope claims that the Platinum converts DSD streams directly to analog—it does not first convert it to PCM. Inside are two independent Texas Instruments dual-DACs per channel, as well as dedicated FPGA processing for its user-selectable upsampling. The Zodiac has linear-phase filters, and its digital and analog circuits are on separate boards, each with its own power feed.

Easy Bake
The Zodiac Platinum includes Antelope's Acoustically Focused Clocking (AFC) with 64-bit DSP, which uses what the company calls an Oven-Controlled crystal oscillator. Oven-Controlled Clocking was Antelope's early claim to pro-audio fame, and the company says that OCC's implementation in the Zodiac Platinum is essential to keeping jitter under control. Antelope's Marcel James e-mailed me to explain that Igor Levin felt that "if he could keep the word clock's quartz crystal oscillator at a constant temperature, he could significantly improve its performance. Igor decided to seal the oscillator inside its own enclosure, thereby thermally stabilizing it."

If Oven-Controlled clocking isn't enough, there's a 10MHz input for Antelope's Rubidium clock ($5995), if you're so inclined. At press time, the company was also promising to ship their new Audiophile 10M Atomic Clock (advertised on the company's website for ?2104 or $8293.50) as an option, in a case similar to the Voltikus power supply.

On the Case
The first thing I noticed when I received the Zodiac Platinum bundle was its beautiful, thick, shiny cardboard box with color photos and, inside, ample padding for the components. Included are a pile of cables for most connection scenarios, including a nicely made DC power cable, the all-metal remote control, and the two components: the Zodiac Platinum DAC itself and its Voltikus power supply.

At 6.5" wide by 4.4" high by 7.5" D and weighing 4.4 lbs, the Zodiac Platinum is well proportioned and compact. The Voltikus power supply is smaller (4.2" W by 4.4" H by 6.6" D) but heavier (6.4 lbs). Though the cases are the same height and are both made of all-black metal, their silver faceplates look as if they're from two different product lines. Unlike the DAC, the power supply's front has arcs machined out of all four sides, and small bolts to hold it on. The fit and finish are top notch, but unlike with Antelope's Rubicon, there are no gratuitous metal or design flourishes anywhere.

On the Zodiac's front panel, two small lights indicate whether a PCM or a DSD signal is being processed, and below those are four more small lights, with symbols indicating digital signal lock, atomic clock present, word clock lock (via a BNC connector on the back), and mono mode. Below those is a row of four buttons for, from left to right: Power/Standby, Source, Mono, and Mute.

At the top center, a small screen displays, in sequence, the sample and DSD rates, input, headphone impedance, USB info, and volume level. Only four characters can be displayed, but Antelope has so configured it that it shows you what you need when you need it. When you turn the volume control, the attenuation is shown; otherwise, you see the selected input and the sampling rate—or, during setup, other options.

Below the display is the large volume knob, which nicely fits the fingers and makes a satisfying light ticking sound as it runs through the relay-switched precision resistor ladder attenuators, which Antelope claims are accurate to 0.05dB. I love this approach—a hefty, well-calibrated control for a device with preamplifier aspirations—but the volume control produced a bit of a raggedy zipper sound through my system as I raised or lowered the volume (footnote 2).

To the right of the volume control is a button for selecting the output mode, and to its right is a small cluster of lights. Tapping the button switches the volume control between the two ¼" headphone jacks below the button (a small LED above the jacks then lights up) and the preferred output on the rear panel (one or three LEDs next to the button). It took me a few seconds to figure out how this output button works, as it was defaulted to the headphone jacks and balanced outputs. Finally, I realized that when all three of the top LEDs glowed, that meant balanced output; when one LED lit up, that meant unbalanced output; and that I had to hold the button in to switch between those modes. In any case, it's all in the owner's manual.

On the rear panel, starting at the top left, is the three-pin locking jack for DC current from the Voltikus power supply. Next to that are two sets of analog inputs: one pair for +4dBu pro-level equipment via ¼" jacks, and one pair for unbalanced consumer RCA connections. Next are the balanced (XLR) and unbalanced (RCA) analog outputs. The bottom row is all digital, beginning at the left with a BNC connector for an outboard clock, two S/PDIF and two TosLink inputs, a USB jack, and an AES/EBU three-pin input. To their right are an AES/EBU three-pin and two S/PDIF RCA outputs.

The Voltikus power supply has a single red LED on its front panel; on the rear are the fuse bay, power rocker switch, and IEC inlet for the detachable AC cord. There's a switch to lift the ground (never needed in my case), and below that is a three-pin socket for the connector that supplies 18V DC to the Zodiac Platinum.

Footnote 2: Jeffrey Touzeau, Antelope's representative, sent an email to explain that "The 'raggedy zipper sound' is due to the stepped relay technology which provides the highest transparency and most accurate stereo image at all levels. The step relays are an industry standard for mastering rooms which proves their high quality."