USB Amplifier

A lot of audio equipment has a digital input (optical or coax), very few computers have a digital out . Apple and of course Toshiba are the ones I know having a headphone out doubling as a (mini) Toslink out.
Every PC has USB but very few audio equipment has a USB input.
Except of course for the USB speakers but these are targeted at the desktop.
Slowly but surely DAC's appear on the market with a USB input.

Amplifiers supporting it all, USB, SPDIF and the normal analogue inputs are rare.

Audio Space

Mini Galaxy One Stereo Integrated Amplifier ($899,-)
Output Power : 2 x 13W (Ultralinear-Class AB Push-Pull)
S/N Ratio : >88 dB
Output Impedance : 4, 8 ohm
Input Mode : RCA / USB (For PC, I Pod)
Vacuum Tubes : EL84 x 4, 12AX7 x 2

USB specs not available on the website so probably limited to 16 bits/48 kHz.

Chord CYAN Click Digital Integrated Amplifier

Unbalanced Input: 1 pair RCA phono

Balanced Inputs: 1 pair of 3-pin female XLR inputs

Digital Inputs: Coax BNC, TOSLink Optical, B type USB

Wireless Input: Bluetooth A2DP

Signal to Noise Ratio: -90dB all inputs

Frequency Range: 2.5Hz – 200kHz (-3dB)

USB specs not available on the website so probably limited to 16 bits/48 kHz.

Price: $8500 High Power Version (100W rms)

Bel Canto Design e.One S300iu

Integrated amplifier with 300 Watts of dual mono balanced power capability per channel.

USB specs not available on the website so probably limited to 16 bits/48 kHz.

Benchmark

Benchmark USB DAC1 Pre ($1595,-) with USB (24 bits/96 kHz), optical, coax and analogue inputs (24 bits/192 kHz)

They also offer a complete system, USB DAC with pre-amp, a pair of speakers (Dynaudio BM 5A bi-amplified studio monitors), that's all what is needed. The computer is not included. Small detail, Dell is know for delivering PCs with faulty audio drivers!