I'm exactly in the same position....all these different versions turn me nuts
I remember that ages ago I compared my MDR-CD1000 to the DT880...I found the 880 more bassy, the treble much less annoying and a lot more comfy.
thing is, I'd like to have truly closed cans...the SONY are not really closed, and the 880 are semi-open.
more bass would be good too, even though I shape the audio the way I want it in OzoneMP
so that leaves me between all the different builds of the 770....some say the pro is harsher, some say the pro/80 has too much bass, some say the pro/250 is more balanced.
and someone said he plugged the 770pro/80 and the 770pro/250 in the same source, and the volume control was set to the same level.....so WTH does the impedance has to do with anything(my SONY is 32 Ohm BTW)
I use the bit-perfect headphones output on my M-Audio Audiophile USB(NE5532 opamps)...it sounds great on the SONY, but the damn thing is too "hot" for me...I want more bass and less treble.
I might settle down to the 770 pro/250, and increase the soundstage in OzoneMP