It's dirty pot. Just turn the volume wheel back and forth repeatedly until the noise gone.

I've tried Soundmagic E80S in either CTIA and OMTP mode, both works fine with E10K. Different TRRS standard shouldn't be an issue, E10K does not support mic/remote input after all.

Different model name actually. The standard one is EX750, the mic+control one is EX750AP and the one with noise cancelling is EX750NA. There's also bluetooth version EX750BT. On another note, how is it compared to your XBA-A1?

I've tried AVC200 and 500 on a local store so I might share my impression. AVC200 is very warm yet not dark, but the tonality is weird, it's like they have too much boost on lower mid, probably around 500-1 khz. Bass is there but lacks impact. Rolled off high. Not much soundstage nor separation...

I found putting the cable behind neck, with chin slider pulled all the way up, stops it from wobbling. Also looks more "professional" because, well, that's how pros use IEM :p

Yeah, roughly a percent every 2-3 minutes. At least one less brick (power bank) to use my E10K anywhere.  

  Look what I've just found out. The E10K running straight from my old Xperia M... without any external power.

So has anyone tried recabling or at least open the housing? Just curious  

I don't have M40x in possession, but from my memory IM70 sounds closer to M40x than IM50. IM50/70 have thicker, more forward mids and smoother highs than M40x. M40x has better separation (as expected from IEM vs headphone) and the bass goes deeper.

No idea, never heard those.

  As ozkan said IM50 is quite different from MH1C, also MH1C is subbass emphasized while IM50 is more midbassy. However I found the forwardness of IM50 is more engaging though, YMMV :D If you looking for similar MH1C signature try Yamaha EPH100 or RHA MA750.

Well figuring mostly, but PG1's official Japanese page states it uses the PRO5MK3 pads. The whole headband and its golden lettering, also the golden ring on the cups look similar.

It's actually a modified version of PRO5MK3, not the M20x.  

If you want a tighter fit, A500X might not satisfy you. AT Art/Air series are known for their loose, hit-or-miss fit. Especially you said M40x isn't tight enough...

Has anyone compared E10K to Audioengine D1 or uDAC3? Just curious