You'll have to take my non-audiophile word for this, but I'm now convinced there are at least two different versions of the X2. My WOOX and Gibson pairs sound far too different to be considered the same sound signature. Disclaimer being that my WOOX pair have a 3-4db imbalance in favour of the right cup aswell as having about 30~ hours on them.
WOOX pair the vocals are more forward and the whole signature is quite bright in comparison to the Gibson, which almost sounds like I have a bass boost switched on when listening. The mids are recessed and the whole signature is way darker than the WOOX - "it's not even close", as they say. It's more difficult for me to make an assessment on the soundstage or seperation because of the driver imbalance in the WOOX pair, but I think it's at least pretty close.
I'm not saying one is technically worse than the other, because I don't know, but take into consideration which version you have when commenting or reading into the statements of others. I can totally now see why some (WOOXers) say these are sometimes shrill or Gibsoners say the bass bleeds into the midrange. I'm also assuming most of the early reviews of this headphone were the WOOX version.
I will stick my neck out here and say I prefer the Gibson pair myself.. but it'd sure be interesting to hear a WOOX pair with no imbalance. If you believe in burn-in then disregard everything I just said.
Hope someone finds this useful and it'd be great to hear from someone else who can A/B the two 'phones.