I remember Rob stating that a cheap TOSLINK cable is as good as anything with the CH2 and that it is no different than USB.
I have similar experience with the Hugo. Initially I tried the USB connection -> audioquest Carbon + iFi Defender (it was an improvement over the stock USB cable dough - less bright and more body to the sound) then, just out of curiosity I plugged in the stock Toslink cable (cost 3-5$ ?) and the sound quality was practically identical, possibly (as the difference was very subtle if any) , the optical connection was even a tad more fluid/more cohesive and less edgy, plus, there is no galvanic isolation issue anymore (if that bothers anyone).
Finally I sold the USB set and happily listen via the optical (TOSLINK) since.