I'm currently on my second pair of M4's. In both, the left side driver has had mid range distortion at higher volume levels. According to mp4nation's website (presumably accurate), the M4 only has a continuous power rating of 4 mw, compared to even the M2 at 10 mw. Sennheiser's website doesn't...

One of the first differences I've noticed between my long used CX300's and my new M4's, is that when I achieved a good seal with the Sennheisers, it would feel neutral in terms of pressure. The M4's I seem to have a difficult time getting a good seal without feeling negative pressure or suction...

I had read that driver flex is to be expected with these, but how much is too much? When inserting these into my ears, the popping and crackling from driver flex is startlingly loud, sometimes almost painfully so (and I tend to listen quite loud). I am particularly concerned because I am hearing...

I have done an extensive amount of reading on this site and others, and spent literally hours in the joker comparison thread. I feel like I have far more options now than when I started researching. I currently have the CX300 (first version), and I do enjoy the sound signature; I have other...