If you talk to other m80 owners, they will play louder than most people can handle. It is possible that many people are using seperates with larger amps to drive them, which would play louder than your Denon.

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