The Oppo has great analog sound quality (perhaps better quality DACs than found in many receivers). That isn't the issue. The limitation is you have two settings for the cross over: Off or 80 Hz for all channels set to small.

I've found 80-all-around to be a pretty good fit for me; even when I'm given a choice.

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris