Far worse than the "quality" of the chip, is the matter of the environment where it is sitting: If you have a DAC sitting on a PC MoBo, it is surrounded by CPU, video, Ethernet and RAM chips that are pumping out high frequency noise; it gets its power from a chopped DC converter; and it is sitting next to a fan (dare I mention fans again) that throws out a rotating chopped E/M field. In such an environment, even the best DAC chip in the world would be dead in the water...
This is a good point. For people using separate amps (at full gain), with the 64-bit volume control, may experience the poorer noise floor (usually around 80db) and not least the noise from CPU throttling and the GPU etc. At least if using analog out. Digital out/HDMI is another matter. Proper hardware choice may eliminate this (not least a proper, efficient PSU).
Anyway I think the idea with JRiver HW is great.
Best regards,
Mikkel