Drew, the m80's have been driven in lab tests at 700 watts continuous for 2 weeks, 24hr/day, and peaks upto 1,000 watts. I think the problem, and you seem to ignore others above that have a wealth of audio/engineering experience, is that your limiting the current of your receiver. To little power is a lot worse on a speaker than to much.

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