Now seriously, some friends came with a T1 to my place. We tried it on low impedance amps like the Beta and the Gilmore Reference (GS-X like, Justin would know better) on highish impedance ones like the Luxman P1 and the Rudi RX-100. With none sounded good, it paled compared to the HD800, HD600 even K-701, especially on the treble resolution and extension. Also kind of "generic" bass, tending to be just one note. Voices were just average, far from a believable sound with a proper timbre.
The 880 is just OK, a bit too bright for my taste, but probably acceptable for the money.
770 and 990... well, too far away from neutral to consider them half seriously. DT-48 definitely a POS not adequate to listen to music. Good to make clinical pure tone audiometries. I haven't listened to other models, maybe it's true the models Tyll defended are OK, but for a company which so consistently makes headphones far from my liking, frankly, not worth the benefit of the doubt.
I still wonder if the T1 or 880 are worth the effort they require to sound good. IMO the HD600 can do a better job without all that hassle. Probably the HD800, with their fame of being tough boys, are easier to get right than the T1.