An introduction to computer audio
Modern USB audio interfaces are USB audio class 2 compliant.
Asynchronous mode, external clock and galvanic isolation are the things to look for.
The Edel USB to I2S/SPDIF interface is an easy to integrate OEM solution for High End USB audio playback systems, supporting both USB Audio Class 1.0 and 2.0.
OEM Combo384 Module - USB class 2 to I2S 32bit and DSD output Converter
Supported Sample Rates: 44.1Khz 48Khz 88.2Khz 96Khz 176.4Khz 192Khz 352.8Khz 384Khz Output Format: I2S 32bit and native DSD 2.8224 Mhz - 3.072 Mhz - 5.6448 Mhz - 6.144 Mhz Oscillators: 2 Low Phase Noise TCXO
Note DSD output enable line to signal an incoming DSD stream.
The card supports output mode only.
NO Drivers needed for Mac OSX 10.6+ and Linux with UAC2 compliant kernel KS/Wasapi/Direct Sound Drivers for MS OS Xp to Win8 32-64bit included at no fee.
exaU2I Multichannel Asynchronous USB to I2S Interface -
Asynchronous operation is achieved by using fast FPGA control core, 256 kB FIFO memory buffer and proprietary ASIO driver.
Galvanic isolation of the I2S output from the FPGA core and the USB ground virtually eliminates jitter and common noise originated by the PC. Isolation is achieved by using Giant Magnetoresistive (GMR) Digital Isolators. The barrier capacitance between the board circuits and the I2S outputs is 17 pF.
The I2S output is powered by the external DAC power supply and it is completely independent from the USB power supplied to the board.
Two precision quartz oscillators allow very accurate clocking with minimum jitter for the 44.1 kHz and 48 kHz sample rate families.
Two voltage regulators with low-pass filters provide low-noise power to the FPGA core and the two precision quartz oscillators. This further minimizes jitter and noise.
Custom designed ASIO driver provides automatic sampling rate switching and bit-perfect data transfer. The exaU2I USB ASIO driver operates in asynchronous mode and it is completely independent from the Windows sound system
WDM / WASAPI support is available by using a third-party native Windows driver - Virtual Audio Cable.
The USB-I2S Module is a implementations of the Audio Widget open source project.
It is a fork of the SDR Widget project.
UAC2 and ASIO driver for Windows are open source.
Basically a USB to I2S converter. Optional support for SPDIF/ADAT/MIDI
DSD: XMOS supports the open DSD standard.
A beta is available.
Group Link USB audio 2.0 (24bit / 192khz) module
The chipset is used by third parties to develop OEM modules.
A massive tread on diyAudio
Asynchronous USB-to-I2S interface
A audiophile PCI to USB card with ultra low noise regulator for digital, clock, PLL and USB power circuit and ultra low jitter clock for USB clock.
Compliant with USB 2.0
All ports can handle high-speed (480 Mbps), full-speed (12 Mbps), and low-speed (1.5 Mbps)
32-bit 33 MHz host interface compliant with PCI specification revision 2.2
NEC uPD720200 chip with low jitter TCXO and output transformer.
This output transformer is hand made with multi cores silver cable.