I ran three M3s across the front in our old smaller house, and they were an ideal set-up!
I ran them with my sealed sub..a smaller 10 incher at the time...and they were a beautiful thing, although when we wanted to control sound levels when the kids went to bed, the sub was not terribly missed. I normally cross my speakers at 60hz and the M3s are more than happy to sing along.
We had a 27X12.5 ft. room at the time and they filled it with no problem whatsoever with a smaller 55WPC Onkyo 5.1 receiver.
I felt they were just ever-so-slightly to the cooler side of neutral, but in no way could they be considered the least bit bright.
I still use one of them as a center along with M50s in our new larger listening room and they match up just great! The M3s produce a very natural sound with voices, and for someone looking for a slightly warmer version of Axioms, the M3/M50 upgrade is a viable alternative.
