I have left Pro Logic II disabled for so long now that I don't recall what results I had with it last, and I certainly have no experience with current firmware behavior. Definitely talk to OPPO about the situation, as the only difference in audio processing I am aware of between the BDP-83 and 980H relates to how it supports expanding 5.1 to 7.1. Both use Pro Logic II for expanding 2.0 to 5.1.