I changed my fronts from small to large, did a quick test and I didn't hear the distortion. Peaks reached 93 db. I've changed a couple of settings and moved the placement of my sub since that post so I wasn't able to re-create the exact scenario again. I also can't remember at what volume (on the AVR) I was listening when I heard it.

It's possible that what I heard wasn't distortion...or that I was hearing things.