I'll be preordering mines shortly although I'm contemplating on whether to go back to CES for one more listen. I spent about an hour at the Hifiman booth yesterday comparing just the HE-400 and HE-500 and felt the 500 was clearly the better headphone, in fact, imho I felt it was quite competitive to the LCD-2 hooked to a Woo WA6-SE @ T.H.E. show at the Flamingo. Also listened to the HE-6 but immediately discarded it due to its insane amount of juice requirement. Getting back to the HE-400, definitely wasn't a slouch especially on the lower range which was nothing short of awesome like when I listened to a track on their portable player titled "chinese drums". Everytime the bass drum was hit, it felt like my brain was getting a massage. Clean, detailed, & punchy. I then connected the 400 directly to my android phone (samsung captivate w/ neutron music player, all flac 16/44 & 24/96 with voodoo control plus plug-in) and the sound was...ok, but the volume, even at max output, was quite low especially with the high amount of ambient noise so I doubt I'll ever hook these babies to my ipod/phone/etc unamped. I just wish they had set up an isolated listening booth like Sennheiser did with their HD-800/700.
Now, I listen to my AKG K702 religiously and still strongly felt the HE-400 was more than worth the $350-400 price tag on a bang for buck basis vs my K702, so only question for me is whether to keep the 400 or sell and upgrade to the 500. Musically, I thought the 400 worked better with electronic, hip hop, etc type stuff whereas the 500 was more appropriate for classical, jazz, acoustic, indie, etc. Just my humble opinion of course; I hope this helps. I doubt any1 could do a serious, full review @ ces, way too much noise interference; I had to crank the amp all the way just to block most of the ambience. Fang told me they're going to ship beginning sometime next week with later orders shipping out by the end of the month so hopefully someone will write an extensive review by then for those still undecided. As for me, I'm getting one no doubt. Worst case scenario I end up not liking them afterall and lose $10 or so to send them back.