A short update.
Now I have my J2 played continuously on ipod 40G for 70 hours. Finally understand why you guys recomemded at least 50 hours burn-in time, because as I listened it last night, it was still bad. But given an extra 20 hours, it finally opens up. I have never had any earphones differ so much before and after burn-in. And I was a believer that "bad earphones sounds bad at the beginning" burn-in process shouldn't make such big difference. Well, I am proven wrong this time.
But here is a catch: the thin flanges come with the earphone are really bad-sounding. This should be the easiest improvement the manufacturer could have done, and it won't cost you a lot. First I changed the stock flanges to ones came with Sennheiser CX300. What a difference it made! Then I changed to another thick clear-type flange, even better.
Now comes to SQ. For the short use, I can only provide my first impression after burn-in. My references would be head-direct RE2 and Yuin PK2 on Rockboxed Sansa E270 playing Flac. I did not change any EQ.
In comparison, J2 sounds not as transparent, but still very detailed. Sound signature is a bit on the warm side. Sound stage is OK. Highs are not as extended, lows lack the punch compared to bass-heavy Senn CX300. Sure these are common in IEMs in this price range ($25 for 2). It is the mids that J2 really shines. Very musical, good for vocals, jazz, chamber musics.
Well, I am not sure whether the 70 hours burn-in had completely pushed J2 to its best condition. I might keep burning-in. But right now, I am pretty satisfied with it, well worth the money I paid.
Finally, some thoughts might be helpful to JLab
I am not sure how many people would take the lengthy burn-in process. If the eaphone does not sound good right out of the box, there is little chance that people would keep it.
secondly, better flanges does not cost a fortune to you, but improve SQ dramatically on your product.
I am looking forward to more and more successful products
