Pioneer Elite A-35r and Magnepan MMG's

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.

i used a pair of mmg's for 12 years; they'll take all the clean power you can hand them. 65w will be enough in that size room... just don't get carried away with the volume control.

This amp will work at low/moderate volumn but will not do justice to the capabilities of the Maggies. I really don't think that your amp is for the MMG's. IMO.

I've never met a maggie that didn't want more power...
Also, 65 watts at 4 ohms isn't much. Personally I'd want something rated 4 times that-100 watts at 8 ohms is easy to find and usually is 200 at 4 ohms.

Like mentioned above,don't get carried away with the volume control.Its easier to blow speakers with a under powered amplifier than a high power amp in most cases.If you go with a low powered amp,I agree about being careful with the volume control.♫