FWIW. My dCS Bartók DAC is set at .2v output gain, the volume control is set at 0db ( all the way up) Roon is also at 0db. Volume is controlled by volume pot on Backert preamp. This gain staging was recommended by Backert’s Andy Tebbe. I would swear that brought about an improvement having the digital gain ; streamer and DAC all the way up.
Digital gain vs analog gain
Is there a rule of thumb that guides the balance between digital input level, analog pre-amp input level and analog amp attenuation for reach your desired listening volume?