I'm assuming that your issue is that you are routing a video source through your Denon and to the TV, so when you select that source to watch it on the TV, you are unable to then listen to music. Is that correct?
If so, you could route a video signal directly from the source to the TV. This would be especially easy if the source has another output and the TV has another free input. You would select that source on the TV, and then the Denon wouldn't be controlling which video signal got sent to the TV - so you could listen to anything that you wanted.
It may also be possible to listen to something different then what you're watching on the 5805. I'd have to check out the owners manual, but someone here may already know.