These are another steal from a4c. I have only had these for a very short amount of time but the arrived quickly and working perfectly. Mine do have a small scratch on them that I wish would have been touched up during the refurb process but I am so blown away by the sound and price it really isn't worth mentioning. I am already planning on buying another pair for a back up. Just like I said in my other review here I am not an audiophile and prefer nicely separated instruments and hard punchy bass. I mainly own iem's due to their portability but do have a handful of what I thought was quality over ears. Within the first hour of owning these they have become my favorite pair of over ears I own. The overall quality of sound is not as good as my beyerdynamic DT 1770 pro's and I didn't expect them to be but they do sound better then my old beats by dre studio's. Out of the box the studio's have better mids and highs but the jbl synchros responds better to eq adjustments and ends up sounding better. I really wish more people would incorporate an eq or and eq app into their listening experience. Just like with the samsung level in it makes a world of difference with these.
These are 32ohm so requires some power to push if you want to listen without the battery powered livestage gimmick. The only cellphones that I have that can make these sound decent without the livestage turned on are made by htc. My iphone 6s struggles to even get these to a decent volume let alone start producing bass. My lg g4 sounds sound terrible all around and without an eq app turning on the livestage function seems to blow out the vocals and makes a lot of songs sound like they are sung in a giant empty room. I wasn't a fan of it till I turned on bass boost in my eq app and immediately my jaw dropped. The empty room sound went away and the bass was the hardest bass I have ever experienced with any headphones to date. I am not even exaggerating when I say the bass gets so heavy the headphones vibrate and you can literally feel the rumble around your ears. I really don't think it is possible to have any more bass in a pair of headphones. It brought me right back to being a teenager driving around with two 12" audiobahns in the trunk. Words really can't describe the amount of bass these can produce with the livestage turned on and an eq set to boost the bass. Even with the absurdly exaggerated bass everything else is still crisp and clear.
The highs and mids are good even with the bass boosted and with some fine tuning on the eq these trade blows with headphones well above the current price as well as their release price. You can get an audiophile sound out of these if you have an amp or decent sound system and can adjust levels while leaving livestage off. Using my external dac on the pc and leaving livestage off it is impressive the detail these pick up. Imo the livestage function on its own degrades the quality of a song and in that sense is a failure. My opinion of livestage while using an eq app is completely opposite. I absolutely love it because it also seems to act as an amp and if you use the eq app to offset the strange effect created by turning livestage on you get a great sounding powerful experience.
I started this review at a loss for words but like I do I rambled on till it was too long. I'm going to try to sum it up. Always have a form of eq on your listening devices and these are a must buy for those that do whether they are audiophiles looking for a cheap beater headset with great sound or someone who loves bass and finds more bass the better. These pick up and rumble all the way down to 10hrz and that is just the lowest test frequency I could find. Whether you buy refurb or new the deal is good. Also invest in a set of AAA eneloops and a charger cause once you mess with the eq and livestage you probably won't turn it back off. Yes these take two AAA batteries and not AA batteries like listed at the time of purchase and this review.