I've owned the TH600 for 2 weeks and I am very impressed with it's U-shaped curve. I had the HE-4, HE-500 and LCD-2 rev1 & rev2 for 6 months each prior to the TH600. The top end of the TH600 is better than the LCD-2 or HE-500. The soundstage depth of this closed headphone is on par or better than the HE-500 or LCD-2. The bass of the TH600 has better texture while the LCD-2/HE-500 do have better impact and speed. I feel that the TH600 is an excellent all arounder headphone, better than the LCD-2. HE-500 is kind of a toss-up because I liked it with most genres of music. The TH600 also fits the same criteria. I had the HD650 and HD600. I would easily pay the extra amount of money for the TH600. Just better detail and high/lows. I didn't find the midrange of the HD600 nearly as refined as that of the TH600. The HD650 midrange may have been more palpable for piano than the TH600 but timbre goes to the TH600. I haven't listened to any flagship dynamics. Naturally take all of this with a grain of salt because I didn't own all of these headphones at once but going off of memory I'm just stating my opinion of the TH600. I've tried a couple of the new Audio Technica midrange offerings (ESW9a, WS99, AD900X) and while good they do not offer the detail, bass and sparkle of the TH600.
I am curious about the TH900. One thing that might stop me from trying it is a return to the orthos. I may just put off buying that HE-6 and enjoy the TH600. Save up and eventually have both in the lineup. If the TH600 had the midrange of the orthos then I would take this lightweight, comfortable headphone over most things in its price range. Fostex has a winner on its hands here. In the shadow of the TH900 it is hard to live up to big brother.
Edited by WNBC - 5/27/13 at 10:04am