First impressions: Instantly comfortable - no pinching or adjustment issues. Very spacious open sound, and somewhat bassy. Set bass reducer EQ and bass is good now - still deep and good impact, but tight. Some things are more prominent than HD-800 such as the ticks (drumsticks?) in the Beatles' And I Love Her stereo version. I don't hear any peaks anywhere in the sound, but it will take longer to evaluate whether there are any, and whether burn-in will make a difference. Detail is very good, but impresses me not so much as technical detail, more like musical detail. That's a good thing. I don't hear sibilants as much as the Shure 940 or Senn 800, but these are not soft on the high end - they have a lot of energy up there. How a user would perceive the highs will vary according to whether they play these flat or adjust the EQ. The good is after reducing the bass, I still don't perceive any high freq. problems or midrange peaks or sibilants, so they're pretty smooth. But compared to the Shure 940 they are more forward, noticeably so. But using my test for nasal effects - no problem there. Lastly I ran through a series of discrete tones from 100 hz to 12 khz (each 1khz from 1 to 12), and the amplitudes varied, but not a lot. I'd say that 2 khz is noticeably louder than 1.5 khz or 3 khz.