I have 10 hours of listening with the Denon D2K and I have noticed a change. I have a different bass signature now. The bass now is more precise, more delicate and better. I also found some peculiar distortions on certain songs. These songs are lossless FLACS and out the box they did not distort. Did the break in process modify the upper end of the cans as well and now they are more sensitive to excessive treble? I am not sure but until my FiiO E11 arrives, I will have to assume its the Nokia N8 and the iPhone 4 that distorts at high volume.