Actually the sound quality is not that big, -maybe- a bit better with the E11. But the difference in the amount of volume and bass IS huge. I'm really surprised how much bass the M-100 can take without any real distortion, despite some muddiness of course. Blows the COP out the water for sure imho.
Yea, I have been noticing people comparing the m100's to more $200 dollar headphones than $300.