Hey, thanks for the response.   By S/PDIF I assume you mean the optical output, since the u7 has not optical input. Good to know.   So, when adjusting the volume, does it adjust the system volume on the Mac? Or is the volume 'post-dac' stage?

Thanks for all the great insight on this DAC / Amp, I'm strongly considering purchasing it in favor of other external DACs such as the Audioengine d1 or Aune models.   One question I had, for owners of the device, is regarding the volume control. Is the volume control 'software' based, i.e...