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 DACs appear on the market with a USB input.
Amplifiers supporting it all, USB, SPDIF and the normal analogue inputs are rare.
A list of amp's with digital inputs can be found here: HTForum
Audio4Soul Xtreme16 USB €1350
Integrated amplifier with 24/192 asynchronous USB input and SD card.
Amplification by PWM (Pulse Width Modulation)
| Inputs: | 2xS/PDIF (coaxial, optical 24bit/96kHz), 1xUSB (24bit/192kHz, XMOS, driver for Win) |
| Memory card | SD, FAT32, compatible with WAV files (16bit/48kHz), MP3/Ogg (128-320kbps) |
| Power | 2x16W |
| Thd+N | 0.01% |
| Other | Remote control, 8GB SD card, USB to SD adapter. |
| Dimensions | 360x145x275 (mm, LxHxD) |
| Weight | 6kg |
April music Stello Ai500 Integrated Amplifier $3495 USD
| Output Power | 150 Watts/CH @ 8 Ohms, 300 Watts/CH @ 4 Ohms |
| Output Stage | Quad Para Push-Pull Hitachi MOSFET Power Transistors, Class AB |
| Power Supply | Custom Made 800 VA Toroidal Transformer 90,000 uF Capacitor Bank |
| Frequency response | 20~45 kHz |
| THD + N | < 0.05 % |
| Volume control | Cirrus logic CS3310 digital volume control |
| Analog inputs | 3 unbalanced analog line inputs 1 balanced analog line input 1 BYPASS input |
| 2 Analog Outputs | Pre-out, REC |
| 4 Digital inputs | COAX, OPTIC, PC USB Link, iPod COAX : up to 192 kHz / 24 bit |
| Front Panel | POWER, BALANCED, CD, TUNER, AUX, DIGITAL, BYPASS, MUTE, Rotary Volume Encoder |
| Full Function Remote Control | |
| Dimension | 460 (W) X 86 (H) X 400 (D) mm |
| Weight | 16 Kg (Net.) |
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.
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.
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: $8500 High Power Version (100W rms)
Classe CP-800 US$ 6000.00 
One of the inputs: asynchronous USB.
Full support of Apple’s iPod®, iPhone® and iPad® range of products.
According to the press release:
"the CP-800 can surpass the performance of conventional disc playback systems," said Dave Nauber, EVP of brand development. "A storage device like an iPod or computer can contain all the data of the original recording, so it has the potential to be an audiophile source," he said. "The challenge is to clock that data into the D/A converters at precisely the right time, which the CP-800 achieves through newly-developed recovery and clocking technology."
Available late 2010
Electrocompaniet PI 2D Integrated Amplifier €3.150
2 x 100 Watts integrated amplifier.
Digital inputs: two Coax, two TOSLink and one 24/192 asynchronous USB
Analog input: 1 balanced XLR input and four single ended RCA inputs.
Technical specifications:
• Input impedance ( Single Ended ): 60 kOhm
• THD + N: < 0.005%
• Output Impedance: < 0,03 Ohm
• Frequency response: 1 – 225kHz
• Channel separation: > 120 dB
• Noise floor ( 1Vrms, 20 - 20 kHz, balanced): <-130 dB
• Damping factor: >300
•Rated output power
8 ohms 2 x 100 W
4 ohms 2 x 165 W
2 ohms 2 x 220 W
Dared MP-5 €330
13 W integrated amplifier.
USB specs not available on the website so probably limited to 16 bits/48 kHz.
Luxman DA-200 USB DA Converter $2,199.00 USD
Pre-amp / headphone amp with analoque and digital inputs.
Single ended and balanced out + digital out.
COAX/OPT input: 32kHz, 44.1kHz, 48kHz, 88.2kHz and 96kHz, 176.4kHz and 192kHz
USB input: 32kHz, 44.1kHz, 48kHz and 96kHz
16 - 24bit 2ch PCM
Outlaw Audio RR2150 Stereo Receiver US$ 699
100 W stereo receiver with USB.
USB specs not available on the website so probably limited to 16 bits/48 kHz.
Peachtree Audio Decco65 US$ 999
Amplifier
Class D amp modules 65 watts per channel <0.5%
distortion into 8Ω, 95 watts per channel <0.5%
distortion 4Ω, 20Hz-50kHz +/- 0.1dB
Preamplifier
Hybrid tube design (triode 6N1P) 5V output @ 2.0V input
Max output: 7V rms / 11.2V peak
Class A output stage <50Ω
Headphone Amplifer
Class A output with 6N1P tube in the circuit
Maximum output power: 100mW into 8 Ohm / 300mW into 150 Ohm / 150mW into 300 Ohm
Output impedance: <30Ω
Suitable for all electrodynamic headphones
DAC
ESS Sabre 9023 Upsampling 24/192
Sampling Rates : 44.1, 48, 88.2, 96, 176, 192
USB Asynchronous up to 24/192
Optical Up to 24/192
Coax Up to 24/192
<3ps jitter measured at master clock
Wadia 151 PowerDAC US$ 1,195.00
Inputs: 2 Coaxial S/PDIF (RCA), 1 TOSLINK optical, 1 USB. All inputs, excluding the USB (24-bit/96kHz), can accept up to a 24-bit/192kHz
Power: 50 watt/channel 4 Ohm, 25 watt/channel 8 Ohm
Dynamic Power Rating @ 1kHz:200Watt/channel 4 Ohm
Distortion (THS + N):1kHz at 1Watt: 0.03%, 1kHz at 45W: 0.11%
Signal-to-Noise Ratio:-103dB (signal on), -105dB (signal off)
Frequency Response:20Hz to 20kHz ±0.7dB
Wyred 4 Sound mINT US$ 1,499.00
Mini-Integrated amplifier
DAC: ESS
Inputs:
2 analog
S/PDIF 24 bit 192kHz
Asynchronous USB 24 bit 96kHz
Outputs:
Pre-amp out
Headphone out
ICEpower amp 100 wpc in 8 Ohm