DT880's, being paired with a tube-amp do not need any EQ. If you don't like this sound, change the headphone. Same goes to HD650's and K701. On this level of fidelity, EQ-ing isn't a good idea. Believe me, I had tones on experience with EQ. It works out during burn-in period, but after 200 hours , when you turn your EQ off, the stock sound makes you happier.
Except for all headphones need help in the bass department. I'm sure half of the people here are fine with EQ-less music and average bass, but I actually like to push headphones to the limits of what they can do.