To add to Ken's advice re ohms....your sub will be picking up the lower freq's as well, where some of the "dipping to 4 ohms" occurs. You should leave your receiver at 8 ohms, Denons, HK's and Onkyo's should have NO trouble driving the M80s at reasonable levels. M80s are actually easier to power than the M22's, btw.

Half of communication is listening. You can't listen with your mouth.