Having tried many pads on different cans, I can say that how pads affect the sound can make it a "one man's trash is another man's treasure" experience. Based on that, I wouldn't discount the HM5 pads out of hand. Given
@Sundown's problems with the stock pads, and based on my experience, I'd say the HM5 pads are worth a shot at $20 (if you can still get them from Amazon at that price).
Acoustic mods using Creatology foam or whatever + your imagination are ridiculously low cost, don't require much effort, and if done correctly are completely reversible. One example: I taped some thick Creatology foam rings to the underside of my stock pads, as I wanted more room inside. The result was a slight tweak of the stock sound. The HM5 pads do change the sound more noticeably, but for me that was a good thing.
YMMV, of course. All I'm saying is don't discount something before you've tried it yourself.
@Sundown
I'd try the serious washing mentioned earlier, with an eye to the HM5 or some other 3rd party pads. I'd be curious how the washing goes, as well as any other pads that fit and work with the X2s.
Good luck