Firmware makes a significant difference. 2.0.2. was bass-heavy (in a good way), but a bit too smooth and didn't have the imaging and attack of 2.2.0. I'm glad I didn't get rid of the Ref7.1 prematurely to get the M7. The Ref has solid bass, quite a bit more than the 2.2.0 PWD MK2.
3/16/13 at 9:36pm