Shazam - I understand what you are trying to do. There is just no solution out there for this. Also, there are no USB converter or DAC solutions that are completely jitter insensitive IME.
What you could do is use the S/PDIF or AES input on the USB DAC driven from a reclocker like the Pace-Car sourced from the Sonos. This will match or beat the quality that you get with straight USB. This would be driven by Superclock4 rather than an inexpensive oscillator.
Steve N.