I'm glad someone bumped this thread again!
Been listening to mine non-stop almost since I got them (third pair). Still think these will never make bad music sound good. I think the Q701 actually DOES do this sometimes. It seems to be a little bit forgiving of very badly recorded music. Sure, if it's harsh and fatiguing IN the record, then it will sound that way.
I've been using them for awhile with my Headroom Micro Amp + HRT music streamer and they just didn't sound the same. I connected them up to an old Panasonic portable CD player and a portable amp and they're back to their old self.
Can't believe how detailed these are. I'm pretty much now positive these actually have more detail than my Q701, but it would take a lot of work to know for sure. I think these perhaps have just as much detail as the DT-880, if not more.
So far what's impressed me other than the detail and sound clarity is how good the soundstage is. It's completely accurate based on how the actual recording is. For example, in some music it sounds like male vocals are recessed, but in fact the recording itself MAKES it sound this way. Pearl Jam is one example. This pair doesn't really have the "relaxed mids" of my old pair. The sound out of these is very fun, but still very, very balanced. When the recording feels as if it was made in an airplane hangar it kind of sounds that way, but doesn't get as large souning as the Q701, but does a good enough job.
If they keep sounding as good as they've been sounding, this pair might top my DJ100 as my favorite headphone of all time. The 8400 does get more things right, but doesn't have the bass or more forward mids of the DJ100 (which is a good thing sometimes). DJ100 mids are just far too addicting to me. Kind of like how my Grado SR-325is is.
Haven't felt interested in comparing the 6400 to the 8400 any more. With the 8400 I don't feel like analyzing and comparing them much. I guess that's the sign of a near perfect headphone!
This cable definitely seems improved. Not sure how, but as mentioned before, if you get it tangled or wrap it up, it doesn't retain that shape for a week like my last pair did!
Another thing I noticed is that the comfort of these gets better the more you use them. it seems it takes awhile for the pads to kind of stretch out for a better fit. I know this sounds hard to believe, but I noticed this on the 6400 too.
Now this is weird...
First pair sounded like it had way, way too much treble and seemed to effect it's overall sound too much. Kind of like the AD700's treble makes everything sound a bit "off".
Second pair sounded great out of the box and needed no burn in. Smoother treble than my first pair, but pretty much very similar. This pair sounded so close to my KRK KNS-6400 that it took some major over-analyzing to tell the difference.
With this pair (that has new packaging and everything) it seems to sound much more different than the 6400. When I first compared the old 8400 to the 6400 it didn't feel any more warmer, fuller sounding or "musical". Yet, this pair fits that description perfectly. IMO it's probably warmer than the Q701, but not like the SRH-840 or say a Sennheiser. The 6400 I have is a lot thinner sounding (not in a bad way!!) than this 8400. I guess it all depends on what one likes in a headphone. So it looks like I finally got a pair that sounds like the versions everyone else is hearing!
Did anyone ever get a pair without the plastic shell packaging? The first two pairs (very early pairs)I had had ZERO plastic bag over the headphone or no shell. Just the headphone in a box and a piece of foam attached to the flap that secures it in place. Could be that BOTH my early 8400s were in the same batch. Got both at Guitar Center.
I'm also happy that I was able to get them to give me more clamping force. It was a huge risk, but they made it through the process! Kind of scary and I won't explain! Still not secure enough for exercise, but who does that with a studio monitor?! At least I can move my head all around without them falling off.