@big_greg
if I play the SACD in my Oppo player and the sound from the internal DAC in the Oppo is clearly worse than if I play the red book version from the same SACD disc in the CD player in my Rockna server through my Rockna DAC
I don't know what Oppo you have but I guess you spent 10 times as much on your Rockna DAC alone. You may not have compatible cable connections, but I would be very interested in how 2-channel DSD played from your Oppo (acting as a transport) sounds through your Rockna DAC?
From my reading, the Rockna DAC does not appear to process DSD natively. Instead it converts to PCM which negates the inherent linearity advantage of DSD.
My Reavon, which is basically a repackaging of the Oppo system-on-a-chip, has TI Burr-Brown DACs which also do not process DSD natively. It is hard to tell from the blurb because you have to read the DAC spec sheets carefully, looking for what they don't say!
But when listening, I could tell almost immediately there was something wrong, which was confirmed when I wrote to Reavon. It is fine when used as a transport feeding native-DSD capable DACs.