IMO, Denon's build quality has dropped off substantialy since 2008. The 33XX series was on par with the old 28XX series. I would get the Onkyo 818 and be very happy with it. I've heard the 818 with M80s and it sounds great, doesn't even get hot.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70