Since I've had the Total AirHead amp, I have loved the sound my AKG K701 produces. I hated the "instruments and voices sound lighter than they should" sound of the K701 before that; it was due to lack of amping. Yes, I have all those dynamic headphones in my signature but I never bothered to get a decent amp; well, I have a Xenos 0HA-R, but lost the adapter a while ago, and my E-Mu 0404 USB has an integrated headphone amp, but it is apparently worthless. My opinion on the K701's sound was really strongly negative, too - this should serve as a reminder to look at people's signatures and/or profiles to see what equipment they have before taking their opinions seriously. On that point I realize that I am still in the utterly low-end when it comes to amp and sources, so my opinions are not worth much when it comes to solid equipment like the K701.
Anyway, this amp has made me totally reverse my "K501 is superior to the K701" view, which I probably espoused in this thread a year or so ago. The K501 is utterly out-classed by the K701 - it is basically a mid-fi versus hi-fi sort of thing. I don't really like my K81DJ either, so I'm not part of "team AKG," but I do consider the K701 to be the best dynamic headphone I own, and I wanted to post my change of opinion somewhere on this site.