I also have the 4806. It is Awesome compared to the cheap Sony I had. When I did the firmware upgrade I had the similar problem of having to recalibrate the system.

Back in September there were press releases about a major firmware upgrade for the AVR-4806 to be released in October, I think. Supposedly it was to cost $250. Has anyone heard anything more about his upgrade?
I emailed Denon several times and they never answer me.

maphiker