You have the QS8's now? Anyway, I prefer a direct speaker which is why I gave up on the QS8's and went with M3's in the back. The QS8's sounded great on movies but so so for music. I'm running the 3805 also but +10? Holy crap. I have my M3's at 0 and they hum right along. Have you run the test tone on the Denon?

Let me know if your running the QS8's.