Yeah, what exactly does it do when you're trying to play an audio CD without the projector on? Is it giving you an error message or anything? There's no reason why any HDMI handshaking should need to go on to play back audio CDs, but that's what it makes me think of, since my HD DVD player would give me an error if I changed video input on the TV or turned off the TV during playback. However, this only affected HD DVD playback, since only they needed the HDMI connection to be complete. It's conceiveable that either the OPPO or the Denon want both the display and the player to have that connection intact at high-def resolutions, though? Try changing the resolution on the player to 480 and see if you can listen to CDs without the projector on, perhaps. I doubt that it's it, but it's worth a shot. Of course it's not a solution to the problem, but at least you'd know what the problem is. Just a shot in the dark!
