This might be a silly question, but if you're using it solely as a pre-amp wouldn't you be better off disconnecting the companion, effectively leaving you with a D220 Pro? I don't see that you'd lose anything, and you'd then be able to configure a stereo pre-out.
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK