I just got a pair of the M100's in a few weeks ago. I have noticed a couple of times with a couple specific songs in audio only I believe that the song makes what I believe is the mids rattle or vibrate causing an unpleasant sound. I haven't isolated it specifically but am a little concerned 99.9% of my music sounds just fine, I am confused as to how a few tracks can cause this but most others not? Any chance it is a hardware issue?

If they are ripped music and compressed, it is possible it is that, and not the speakers. If you say the other 99% of your music is fine, it could be the source.

I had loose binding posts on the back of one speaker one time(not Axiom). One note on one song on a Nora Jones dvd made it vibrate like a kazoo. I have never tried this, but I wonder if you could isolate it with an automotive stethoscope.

Can you get a copy of the same song from a different source? I had that exact or extremely similar effect on a couple of individual tunes I bought on iTunes. I eventually found the original CD and the problem is now gone, even after doing my own ripping.

I couldn't hear the distortion in my lackluster truck stereo but my M60s play stuff for exactly what it is. Crap in = crap out. Luckily, the same formula applies for Awesome In.