I bi-amped by M80v2 speakers using a Denon AVR-3805 a few years ago and noticed no significant improvement in sound quality. I ended up buying some new but discontinued QSC SRA 3622 two channel amps that provide 1100 watts/ch at 4ohms. I am HAPPY with the sound quality and volume of these amps! The M80s really opened up with these powerful amps. I do have a very large family/living room area, so the additional power did help with playing music at very high levels.

4 M80s/VP150/EP600/Denon AVR-5308 & DVD-2910/
2 QSC SRA3622(1100wattsX2)/Carvin 1800HD(600wattsX2)