My COP's sound phenominal. They are my first beyerdynamic headphones so I have nothing to compare them to really... but compared to my MDR V6's, SkullCandy MMM's, TMA-1 Studios, and Koss Pro DJ 100's... these are money.
I'm now a die hard beyer fan. They are built like a tank, sound amazing... NO cable microphonics whatsoever so they actually are a good portable (even though they are huge).
They are my favorite headphone in my stable now (I suppose I like a bit more bass than most). They easily outclass everything I listed above, especially when it comes to microphonics.