A good guy to ask about this is skylab. Would personally recomend ignoring most of the beyer fanobys. I have a DT770/80 pro after a large amount of looking + a quick chat with skylab.
Okay, so the pros are black and generally have their ohmage written on the outside of the ear cup (the exception to this being the 250 which i believe is unmarked). The consumer edition (or as I like to call them, the 'uglies') are silver/grey. To my knowledge there is no way to tell the difference between the 2003(?) and the 2005 version of these phones except for sound - the 2005 is generally accepted to be the better sounding of the two in this case (with mids that are less recessed). All of these phones have a strong treble presence, and the pros have a large amount of bass. The general consensus is that the 80 ohm is the best option for the pro (FWIR it has better sonic qualities than the 250 and most people ignore the 32 and 600 IME because theyre manufak only).
Theres also the 770M which has a variable resistor dial on the cable (volume control) which is considered not worth the price as a whole.
the 770/80 is qutie fun for me at the moment but some tracks with poorly mastered bass will sound excessively bloaty- but it works great for electronic music (Like Alice in Videoland and Infected Mushroom). It doesnt work so well for chiptunes or later albums from ladytron (where the action happens in the mids and in the case of chiptunes there is already generally a large amount of bass).
The bass boost is quite large (quite startling at first). I've been playing music through mine for over 300 hours and the phone is a lot more comfortable to listen to now (could be ears becoming accustomed to, though).
You can tame the treble on the pro by underamping it/reducing the current available to it quite easily, but this may cause a tempermental phone that sometimes distorts on tracks and may reduce clarity.
The mids are recessed on all the 770s, but the least recessed would be the 770 consumer 2005. Hope this helps at least a little.
EDIT: a few small-pics that show how much they contrast in appearance
DT770 2005 consumer.
DT770M
DT770 pro This is a 250 ohm version - it says Beyerdynamic)))) on the bar across the cup. On my 80 ohm pros it simply says DT770 PRO [size=xx-small]80 OHM[/size]
EDIT:: and to clarify the general consensus regarding 2003/2005 Consumers, the presentation on the 2005 is more neutral but there isnt a large difference FWIR, probably even less if coupled with a warm amp with prominent mids (probably tube or an SS like the corda arietta) which imo improves the cans quite well (the pros i have, that is).
