audiofan,

The idea in calibration is to get all the speakers to sound equally loud when fed signals of equal amplitude. Also, if you generally sit in one spot when listening to your music or watching movies, then how your system sounds from THAT spot is the most important.

At what decibel level did you calibrate your speakers?

I wouldn't say the M22 is better than the M3 at playing louder, either. Both should be capable of playing at levels of at least 90dB from 10 feet away in your size room, driven with an average amp.