UHF Magazine just published a review of Blue Circle's The "Thingee", USB converter/DAC. It can be used to convert the USB output to another type of interface such as coax, optical, or balanced (SPDIF?) for output to an external DAC. However, in the article they said their "jaws dropped" and "How could it be this good?"when they heard the analog output from the onboard DAC of The Thingee. For $170 to $190 it might be worth looking into.
Good luck.
Good luck.