Maybe the 15 year old Denon was a different product? If you pick up a 3600, 3700, 4500, 4700, 6500, 6700 I guarantee you they all run HOT.
Glad you are happy with yours. My 4500 ran hot from day one. It lasted 9 months before the Height speakers burned out. I sent it in to Panurgy as requested by Denon who kept it for 2 months, scratched the case in front and top, and sent it back with parts rattling inside. I asked for a replacement. It was denied. They have it again... who knows how long they keep it this time. Soon it will spend more time in the Denon shop than in my house.
Maybe someday warranty service will be important at Denon again? According to other users this is not an isolated case.
Go buy yourself a 3600 and send it into Panurgy for Warranty service. You can see for yourself what you get back.