The Z1 uses battery management and never takes more than 600mAh when charging over USB (tested here with various chargers and two Z1s). Hence a more juicy charger won't change a thing.

Beat me with fried chicken, but I can not reproduce this issue. I can plug in and out my IEMs all day long, no pop whatsoever. Thats both in use and turned off. The only thing changed to stock is the replacement of the op amp.

I can only hear a (relatively minor) click sound when turning on/off? (With LME49720NA)

Yes - it sounds better. No - not the same op amps, e.g. the LME49720NA does not work in the Walnut too well (needs decoupling capacitors most likely), it shines in the Zishan... YMMD IMHO there is currently no reason to get a Walnut v2, given the sound quality of the Zishan Z1 and its USB DAC...

In fact both are absolutely identical in size, only the knobs make for a difference in total length. The Walnut v2 has a weight of 98g, while the Zishan Z1 86g. Soundwise its no competition, the Zishan is better, both OOB and amp-rolled optimized.

My Shockwave III IEMs sounds very nice connected to the Z1. They are rated at an input impedance of 20Ω.

Yep! It connects using the std. Microsoft drivers. No need for driver install. BTW I noticed it does not work on XP, but given the age of that OS that's mostly academic.

Definitly not the case here. :) I just ordered a second one.

...works also great as USB sound card (Windows 10 Creators Edition tested) Very nice!

Given my limited understanding of Chinese I ponder it may also mean 'hair dryer', 'large pile of beans' and 'look, there is an ufo behind the clouds' depending on context. ;)

Default is a TI NE5532

16V 10µF (violett) and 100µF (gold).

I am currently testing some opamps in the Zishan Z1. Too early to conclusively tell a winner, only a few comments after a few hours listing and swapping op amps. Keep in mind that there is no 'magic bullet' op amp. It all depends on the environment it is put in and personal listening...

I consider the Zishan Z1 is the Walnut v3 ;)

It depends, with the Burson v5i the multi-BA MusicMaker Shockwave III work surprisingly well.