Hey, I'm in the market for some headphones in the $200-400 range.  I have looked at a lot of models, and I was wondering if anyone knows anything about these new JBL synchro S700s.  I know JBL's reputation for headphones, but I was wondering if maybe they have stepped it up with these new releases....

These apparently just came out, and probably no one here has experience with them yet (JBL isn't too liked around here). The design is really interesting though. Looks like they took AKG's K550 headband design and made some adjustments.

I just got a pair of S700 tonight and listened to it about 2 hrs till now. I have to say if u are looking for superb build quality and good sounding combined headphones in this price range then giving this S700 a try; if u are looking for a good build quality and superb sounding headphones then go for KEF M500. I can't tell u too much coz my S700 are still burning in and my S700 did lay down in front of my door during the cold Canada daytime, and I do suspect the very bad sounding image when I tried them on at the very beginning is because of the cold weather outside. Anyway in my case they sounded much much better after first 30 mins.
 
Plus the Live Stage (?) function, I might be wrong about its name but u know what I mentioned, is very interesting: it lets u feel music is in deed played on a stage when the function is on (I played in a orchestra for 6 years and I am very familiar with this kind of feeling, or should I say a typical JBL speaker sounding?), and when it's off I do feel the vocal is much more forward which is to me a standard listening experience a pair of over $300 headphones should give me.
 
I think JBL now offers free shipping and free return of this S700 on their website for US only, so if u can u should give them a try.

I got them by chance at the beginning of September, after one of the Europe launch parties.
 
I have waited for reviews for them, but there has been only reports of the launch events and PR so far.
 
My only ground for quality comparison is the Senheiser HD-25-II and a little bit of the Beats Mixr. I haven't owned any other proper headphones.
I mainly listened inside and outside with the Senheisers for about a year. They are well known to barely have bass, while having much highs.
I got the Beats Mixer by chance again*. I already had the HD-25 for some time, so I listened to them out of curiosity for several days before selling them to my flatmate. Lots and lots of bass. Is there anything else from bass?
 
Well the S700 are pretty good sweet spot. They have plenty of bass, while the mids and highs don't suffer. The sound stage is maybe a tiny bit narrower than the HD-25 and much larger than the Beats. I like the sound. The bass doesn't drawn everything else. They are not as tiring, as the Senheisers.
 
Ergonomically, the HD-25 are pretty hard on my ears, while the JBL is fine. The option to turn both headphones is welcome, as the headphones come closer and more comfortably to the body.  They are massive, so this is actually essential.
Aaaand they weight a ton. I don't care much and it doesn't bother me, but they are definitely the heaviest headphones I have ever handled. They are made out of CNC'd aluminium!
 
Durability is good. Made out of aluminium, they are solid. I haven't paid for them, so don't care about destroying them and carry them everywhere. They have fallen several times, while commuting with the bicycle. There aluminium body is not easily scratchable, but the edges get scratched easily. Like what usually happens to heavy used black iPhone 5.
 
Now, the LiveStage DSP is total crap. It's optional, the left headphone has a button hidden under the logo, you press it to activate. It pretty much sounds like this builtin software equalisers on the Rock setting.
I works really well with crap quality recordings. If there is a very favourite song that you can't find with good quality, the DSP can actually help. But why keep crappy quality records??
I am yet to hear a high quality song that sounds good with the DSP on. A bit more bass, lots and lots of more mids and everything sounds muffled.
 
I don't have the charging cable (there is a builtin Li-Ion battery, that you charge with USB adapter cable, that plugs instead of the normal 3.5mm cable (on the headphone side it's 2.5mm)), but I don't care, I don't see ever using the DSP. It seems to ad several dBs. It would be nice if it could be used only for this, without the horrendous builtin EQ.
 
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I will mention that the Senhs were a chance as well. Some of the perks in working in mani sound venues with guesting musicians and DJs and their lost stuff...