I have the M22s in a room that is 13.5'x22' with 8' ceiling at one end and 16' at the other. The room opens into the kitchen as well. The M22s have no problem playing loud and still sounding great. As a matter of fact my wife is always complaining about he levels I like to watch movies at.

Mitsubishi 55809
Denon DVD-1600
Yamaha RX-V1300
Axiom M22ti-Main
Axiom VP150-Center
Axiom QS8-Surrounds
Axiom QS8-Rear Center
SVS PB1-ISD