OP,
I will tell you from experience that I have with a similar setup. . . .Do not run that reciever outside of 5.1/zone2 mode.
Once you switch to biamp or 7.1 the volume will cut literally in half. I have called Denon on multiple occasions and they are clueless. so I gave up on biamping.
As far as the volume goes, I have been learning more as I go, but had similar concerns as you do. I have found that when Audessy runs, it will throw your levels to negatives. You can bump the channel volume, but I think I read that 0 is reference level, so to adjust the test tones to be 75 or 85 db at reference level and that is "properly" setup I guess.
Also the dynamic volume thing is another thing to look at. If off, it will bring the volume down. If you select anything else, the volume goes up, which I do not understand and Denon has yet to respond technically to me about.
They sound like a bunch of clueless stoned teenagers so I gave up with them.