Hmm from what I've read, there are a few methods for increasing the friction on the pot. True it's not slim, but it seems to be smaller than most other amp/dacs in its price range.

I got in touch with Leckerton about upcoming products; said they have a UHA4 successor in the pipeline, with better audio performance (and digital volume!).
Also claimed UHA6mk2 having a poweroutput of 75 mW into 50 ohms, and as such would exceed 107db. I'm still going to wait a few months to purchase a mobile piece... if there is no "UHA4 Mk2", I'll just get the UHA6 and upgrade later!

Mine's at least twice as firm as the one on the HP-P1, but not as firm as the RxMK3-B's, whatever that says about it.

Well, maybe it's just mine amp or the fact that I keep it in pants pocket - of course it is mechanical, torque is unspecced and thus has relatively high variability.

So, what's the ancient chinese technique for making the pot stiffer? Perhaps I'll be able to avoid making an exoskeleton for it.