I buy this XMOS USB 2.0 reference design evaluation board from Digikey for US$141.91. It can receive USB 2.0 24bit/192k Fs signal and output to SPDIF optical and I2S besides stereo analogy input/output. The board will require firmware programming before it can be used. Details can be found in XMOS website.
Digikey item: 880-1017-ND
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For I2S, the signal is labelled on the board and I use 2.54mm pin header for connection to my PCM1794A DAC board. The USB board use the power from USB connection at about 150mA and thus do not need any outside power supply. The good thing about the reference design board is that XMOS provide all the details of design, schematic, pcb layout and software to make it work in almost any platform that can accept I2S or optical signal.
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Since I use Windows system and thus I need to install a Thesycon drivers which is also free from XMOS website after registration. The diver works with the USB2.0 reference design boards without any issue but it will beep once every 30mins of use. Overall it is a complete design and easy evaluation of the performance by both industry or DIYers.
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Photo shows how I mount it piggyback on a daughter board and then plug into my DAC main board.
