Okay - well this is welcome turn of events...
I got myself a second-hand pair. 2014 Woox branded. Even after a 6 month+ saga of two returns, I knew from research that this headphone couldn't be bested in its price bracket. Reluctantly I decided to take a punt took and seek out an early production model in the hopes my two glued, channel imbalanced Gibson sets were an unfortunate aberration. It turns out that seems to be the case.
This set has a different sound signature for sure. It sounds far more neutral, balanced and defined. My other pairs were more bass dominant. It overwhelmed the sound slightly, but in that agreeable V-signature type way. That reported discrepancy between what people reported in sound always puzzled me (the recessed/un-recessed mids discussion for example). The others were no slouch, imbalance aside, but these just have that nice roundedness I'd been reading about by fans. What I'd originally been seeking out in the first place.
Materials are different too. The headband seems different to both the other two, though the ear-cushions seem the same as on my first return (i.e. the shiny velour type, as opposed to matte felt type ones). I also perceive no channel imbalance, and honestly, I'm considering not searching for one with frequency sweeps. I'm sure I'd find
something. Ignorance is bliss though; these just sound too good to taint!
I can only conclude that either the sound has changed for good, or my two previous models were from a bad batch; because, oddly, some people report their Wooxs sound the same as their Gibsons.
For me though, it's come as a welcome surprise