Yeah - audio is an even bigger pit than keyboards. I have to say I really like my $179 Sennheiser HD-595s though. Seems to be in a pretty good sweet spot for most modern listeners who don't want to just fall asleep to the typical Sennheiser sound and Von Karajan.
Hmm.... cheaper than a Topre but more than a Filco - maybe this is a Universal Truth!
I haven't listened with the new-issue (late 90s) Beyerdynamic DT-990, which supposedly offer more bass than my old model, but my old (early 90s) one is just (and still!) fantastic, although it wishes to disintegrate from time to time (that's where true quality shows, by the way--you can still get replacement parts for
everything).
I think one of the most important aspects of headphones is not the very best sound you can get, but rather comfort. If they're a pain to wear, you can't enjoy the sound, even if it's the best in the universe. On the other hand, if they sound crappy as hell, even wearing comfort won't cut it (happily enough, no one cares to produce comfortable headphones that sound really crappy), so you'll have to find a sweet spot somewhere inbetween, except when not planning to use them for prolonged periods of time. I have no problem wearing the DT990s for hours, and they even sound decent.
Noise-cancelling is an issue. Active noise cancelling can work, but in order to do it right, you'll need expensive electronics. Half-arsed attempts can produce decent results, though. Filtering out the noise by means of isolating it is far better, as that'll work all the time. Sadly, you'll need closed headphones for that, and I think they're horribly uncomfortable. Open headphones need to have a more expensive speaker design, but they don't rely on sealing everything tight, so they're often (not always!) more comfortable to wear. You won't get any significant noise dampening, though, but I kind of like this as well. On the other hand, I don't work in noisy environments.
-huha