Besides the Oppo, what are your other video sources? The Oppo shouldn't be processed by anything; it should be passed straight to the TV. The only time you really need a video processor is if you have 480i video sources, and even then that TV should handle the scaling just fine. Just forget about processing in the receiver, set it to pass-through and let the TV do the work.

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