65W/channel will probably be on the low side for the Maggies in your size room. If you hear distorted sound then you are probably overdriving the receiver, not the speakers (which could do harm to both the receiver and/or the speakers). In this case moving to a more powerful amplifier (with twice the power) or 3dB more sensitive speakers would likely correct the problem. But keep in mind that if you have a hard floor surface and hard walls that room reflections can cause a harsh or distorted sound as well.
