I have the same problem with them. I own an MH40 non wireless (gen 1 I think). Both the earpads are broken. The glue seems to be coming off after a long usage, so I want to purchase a new one. I see that they have the pads for newer mh40 bluetooth and want to purchase them, but ask support for confirmation.
Turns out "the newer pad is not compatible due to different magnetic structure". Really?
I ask for the older part or if they have 3rd party replacement recommendation for it. No answer.
Last time I'm buying their headphone.
On other note, anybody have recommendations for smaller, foldable headphone that sounds great? The only candidate I can found is Dan Clark Aeon closed
No issue actually. You could simply do that and test whether the sound is good enough or not.
If you're looking for an upgrade, a DAC (without amp is ok since you're gonna connect it to your home amp) should serve you well and typically should sound much better than direct analog connection.
Headphone amplifier should be the last resort. Stereo amplifier might not be very effective at powering headphone, but power wise, they should be plenty enough