Yeah i know one is closed and one is open, but people keep saying all this crazy stuff about how awesome the k702s are and that the next best thing would be 3x its price. So I didn't want to miss out if they are worth it.
The dt770, would I be better off with the 80ohm or 250ohm? I am a headphone newb so I don't really know the difference, I guess one needs more power to get its true ability?
Also what do you think of the Denon AHD2000? Are they dramatically better than DT770s?
DT770-80 is terribly unbalanced- sloppy overwhelming bass, weak mids, metallic intense highs that literally hurt my head. And they get much worse without amplification. DT770 600 is a very different beast and has a reputation for being very well balanced overall, and I've heard some say that the 250 & 600 ohm sound very similar. So I'd say that you will be much better off with 250 ohm.
Owning and comparing the two, yes, D2000/5000 are dramatically better than DT770-80.