Now that we've entered a world of post-disc audio (sorry,
AnalogPlanet.com), audiophile streaming and file-playback products have appeared by the hundreds, and many companies are on their second, third, or even fourth-generation models.
The Chinese company Auralic Limited has been pushing bits around for seven years, releasing a half-dozen streaming and network devices. Their newest, the Altair, combines in a single package the functions of a DAC, streamer, and headphone amplifier with volume control, allowing it also to operate as an all-digital-system preamplifier. Just add power amp and speakers.