It does sound different when stock. However if you do the resistor mods to reduce the distortion, the difference goes away. The treble rolloff will remain tho, thanks to high output impedance, so get good cables.

Do you have a Taobao store or is it just aliexpress only?

I just realized it is possible to reduce output voltage swing without affecting V_bias by changing the value of the 47kohm resistor. This makes experimenting much easier.   So V_bias is kept at 3.85V in my case / R17 still 390R   Trying a few values of R10 / R11, looks like 0.02% THD is...

Interesting to see this thread still alive, with more modding / testing / measurement   I was intrigued by the 0.02% you got, so I tried crocodile clips on just the I/V resistors (No space for the R_bias a.k.a R17) and got 0.04% with 468ohm (paralleled resistors) and a Windows volume of 68...