If it were me having a problem with the 890 I'd rather fix the problem than to swap for the Yamaha. The Denon has much better room correction software IMO. Audyssey Multi EQ is pretty dang good.
You can either bitstream the audio signal (HDMI only) or let the Oppo do the decoding. It should work either way. If the Oppo does the decoding you won't get that little HD Audio light to come on - just in case thats what you were looking for.