I bought an original woox x2, about a month or so later I bought a brand new pair of the x2 not the x2hr.Got X2HR again this year's prime day as I missed the sound and couldn't resist the offer (100$/90Euros). Unboxed it few days ago and what I immediately noticed the pads are somewhat different. It's not shredding anyomore and the material dosesn't attract lint like I remember my previous pair did.
There's also some difference in sound as I remember my first X2HR had definetly better bass extention and more reccessed mids (not that I complainted about it). With new pair mids are more upfront and the bass kicks a little less, however might be because it's brand new.
The new x2 sounded slightly different than the woox x2 .Same as your case, the new x2 had slightly less bass and seemingly a little more present midrange.
My case is not the same as yours since I don't own an x2hr. I think a difference from one iteration to the next might not be uncommon.
However the difference isn't big It's small enough that if I hadn't own the woox, I would still appreciate the x2.
But I like that little extra bass on the woox.