i have a denon, too. perhaps i may help. i have a few questions:
1 - do you leave a good 8-12 inches of space above it a 2-3 inches on the side? if not, try that.
2 - is the room it's in very hot?
3 - are you running your speakers on the large setting? this make it send more juice to the speakers, thus increasing heat.
4 - are you powering low impedence speakers? i power 4 ohm M80's and 6 ohm VP150 & QS8's, so that also creates more heat.
I have been running my denon like this for a couple of months - M80's (4ohm speakers) on large (i have no sub) and i haven't had a problem, and i have a low end denon 1602.
try the suggestions, see if they help
good luck
