mdm
One possibility: You haven't said anything about any possible tone control settings. If by chance you have the bass boosted by any significant amount, then the amp would (or could - depending on source material) start to clip at a "lower" volume setting, thus causing the possible distortion at high speaker volumes. Just because a speaker is rated at 200w - doesn't mean that it and play really loud at ALL frequencies.
If you continue to have problems that you can positively identify as originating from the lows, then you might want to get a powered subwoofer to take some of the very low frequency load off the m22s.
Good Luck
Randyman
