I don't think the bass boost is quite as large in the mid bass as it is down lower. It seems to be concentrated pretty deep. It's most noticeable on songs that feature a significant amount of information below 50 Hz. There may be a little bit of boost in the mid bass as well, but I don't think it's as far above neutral as the sub bass. I'm not entirely sure, though. Like I said, this is a pretty unscientific estimate. Having heard other neutral-ish headphones like HD600 and MD 3.2, as well as many not-so-neutral ones, I can say that this headphone and the HD600 are the only headphones I've used that I never felt the desire to equalize. It sounds just about right to me, fwiw.