On a scale of bass quantity (to what I believe are real world ideas of bass quantity): AD700: 1/10 (audible but pretty much no impact) DT880/ 6/10 (great punch, not a large amount of slam, but well defined and balanced bass) DT990 8/10 (hits harder than the DT880, but it just as quick and punchy, with noticeably more slam) 9s and 10s are those found on boomy headphones like the DT770 Pro 80. The DT880 is an upgrade from the AD700 in practically every way except soundstage... And like Elanzer mentioned, the 'recession' of the mids on the DT990 is grossly exaggerated. It sounds pretty much damn near the same as the DT880s, just that the bass and treble is MORE prominent. It's not like the frigging mids are gone or distant, just not as pronounced. There's bound to be SOMETHING less audible when bass and treble are enhanced. WTF.
If there's something that irritates me on head-fi, it's mid-whores that want the rest to be intense. If you want mids, bass or treble (one or the other) has to be in line. A bass heavy headphone with MIDS is gonna be rolled off in the treble. A treble heavy phone with MIDS is gonna be weak in bass. You can't have a headphone that does all three with intensity. One of the extremities is gonna be compromised. You either get a very balanced headphone and suffer not having the bass or treble emphasis you want, or get a bass and treble oriented headphone that will soften the mids a little. PICK YOUR POISON instead of complaining that a particular headphone is missing something. Do your homework.
Hell, the D7000 I just got is bloody fantastic. It's definitely bass centric, though not overly done so the mids don't take much of a hit, but take a slight hit nevertheless.
The dt880 still has a good soundstage, and better imaging though right?