I'm curious as to what kind of EQ you have on. I know most of us don't have it (I don't have on most of the time) but it's still interesting what kind of sound signature you exactly want.
For example, I just made this EQ according to Tyll's data on the HD668B to give it a flat response and as far as I can tell it works great. Maybe too much bass but that's fine.
Post with your headphone, EQ settings, and resulting sound signature. :)