Interestingly enough the second time I auditioned the HD800 (twice I auditioned it second time I brought my valve amp and found the HD800 took away what I liked about the valve amp - making it sound solid state like????) I ended up purchasing the D7000, one minor reason that swayed me was that I felt upon auditioning that the D7000 equaled the HD800's treble with more bass substance...Now I battle sibilance issues with the D7000, the single most annoying fault of these fine phones.....
Interesting, haven't heard much about sibilance issues with the D7000 (although I haven't heard them, not particularly interested in something bassier than what I have).
Hmmm... haven't think about the 701's in quite a while, but yeah, you are right, not sibilant nor underdamped seems adequate for them.
I've been following very close Tyll's thread, and there are lots of interesting results (and there will be more). It is incredible the practically non existent harmonic distortions of the 650, I wonder if/what other headphones can compare. It is notable the difference of behaviour between 6x0 and 800
But I think it is early to use them for more than educated guesses, I would wait until after CanJam, and until the site for viewing the data gets going, it will be very useful to see some headphones that are not in the Headroom site.
Personally I don't find the midrange of the 650 far from the midrange of the 800, Qualia, K1000 and HE90, which is a lot to say (although it's been a long while since I listened to the HE90), they are phenomenal given the price.
I always wondered if someone suffered from something like what you say. I don't find that strange, in a way it is similar to the way that some people cannot stand more than 5 minutes playing a first person shooter (like my sister), and if I had to guess it's got something to do with psychoacoustics, my hypothesis is that your brain is not adapted to the cues that headphones use, or particularly how they use them (I'm not saying that with any negative connotation by the way), so when you hear some headphones that use them to a greater degree your brain gets tired of trying to adjust to something unnatural. I grew up listening to headphones, so for me they are the natural way of listening sound reproduction. My brain is so used to headphones that it automatically creates a mapping of headstage <-> reality, so whenever I close my eyes I find everything natural, and on the opposite hand of what you say the hd800's headstage is its biggest positive point to me. But I will investigate more on this matter, seems very interesting.