I see this thread is still going strong. I'll contribute with my own experience.
The first unit I received was made by WOOX, it had the older "WOOX" earpads, which either are or clearly resemble the bass pads
Unfortunately, there was a channel imbalance between the left and the right channel and it got progressively worse, so I will be sending it back tomorrow.
Meanwhile, I have also managed to snatch a Gibson made X2, which comes with removable newer and thicker earpads, let's call them Gibson pads or current stock pads.
My conclusion is, QA problems notwithstanding [but as apparent even WOOX made a missmatched pair sometimes] the difference comes strictly down to the earpads.
The Bass pads made the X2 sound like what I expected it to sound like - an evolution of the X1.
The Gibson pads give it a very different twist, making it more akin to studio monitors, such as the AKG K7XX, so reference, analytic and very spacious and detailed.
It is amazing how staggering a difference a rather minor pad change has made here, and the differences between the pads that most significantly contribute are, I would guess, the material [they are made from a different velvet/velour type], depth and foam thickness [the Gibson pads are deeper and thicker], which puts the ear further away and the grill cover mesh [the original WOOX pads have a thicker, denser mesh]. The OG WOOX pads [a.k.a the Bass pads] can be bought on Ebay presently for $39. If you don't like the sound you are getting or want an alternative set of pads, get them. It seems like most of the variance / consistency reported here comes down to that.
As for me, I will be sending the defective unit back and be ordering some Bass pads to get that X1 flavor back
Also, the WOOX pads seem to have a firmer attachment mechanism than the Gibson pads, as those are easier to get off. The WOOX pads also seem to create a better seal as a result [the pad itself extends slightly below the attachment ring, allowing for a better seal].
That's it from me
Cheers