Your friend's Denon is shutting down into protection mode? I have a 2805 which is older and 100 watts and it has never shut down driving my 80's. My room is also probably bigger than your friends at 8,000+ Cubic Ft.

Now, my Denon will go into clipping at some point when pushed real hard, but it has never shut down.

I currently own Odyssey Monoblocks to drive my 80's and the 2805 drives everything else with out a hitch.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85