Interesting...
Tyll @ Innerfidelity:
"You know what chafes my chaps? Makers who discontinue a perfectly good headphone and replace it with something inferior. Denon did it with the AH-D1001 when they replaced it with the very colored AH-D1100. And now they've done it again ... aarrggghhh! The AH-DX000 line has been discontinued and the replacements have arrived. Despite measurements to the contrary, the AH-D7100 highest treble octave seems to have gone missing, and the mid treble is significantly blurred by some of the most horrific ringing that I've seen in a headphone. The AH-D600 fairs about the same, and the AH-D400 is missing it's top as well. I tried to measure the in-ear AH-C300, but the ergonomics of the earpieces made it impossible to insert in my dummy head. I had the same problem with my ears. I'm going to have to add a :facepalm to the smily list. Big thanks to HeadRoom for loaning me the first batch through the door so quickly."
Might this so called "ringing" is what's I couldn't put my finger on what was wrong on the mids and specifically the highs? (this is discussion fom another thread -- Ultrasone signature pros --> http://www.head-fi.org/t/570388/ultrasone-new-announced-headphone-signature-pro/1260#post_8647678 )