Apparently there is a MD2 version which includes an Amanero style usb dac. It supports 384K PCM and DSD256 on usb. https://www.aliexpress.com/item/1005002058252938.html

I replaced LPF opamp (OP275) with OPA1612. Before, sound signature was highly mid centric to my ears. Now it seems more balanced in whole spectrum. I checked via oscilloscope and there is no oscillation or any stability issue with OPA1612.

You mean "optical and coaxial ports, are outputs"? I like Zishan for their high quality PCB design and manufacture skills for good price. I was going to purchase in moment 2xCS43198 version but information on this thread stopped me. I couldn't imagine a "desktop dac" with high quality...

Only 16/48 for USB DAC? I can't believe the waste of the potential. If this had produced as a stand alone or more capable DAC, it would be a big hit on market. What a waste..

These lambskin earpads looks good: https://www.aliexpress.com/item/4000520417437.html

@Maxx134 Thank you for response. I ordered 32 ohm plastic case version of drivers after seeing manufacturer graphs. 32 ohm version is slightly less spiky, then I decided to go with it. There is also 64 ohm version but it is not looking flat as 32 ohm version. I ordered mine at Aliexpress. Here...

I guess you would have a multimeter before attempting such modification. Then, you can track easily AK4493 analog outputs and OPA inputs/outputs. If you don't have SMD experience, I suggest you to avoid that.

So, how did replacing drivers process gone? Can you give a little impression if you finished and listen with new drivers from China? EDIT: Answer is at his/her profile. https://www.head-fi.org/members/maxx134.161988/

I was wrong on this. I tried battery positive cable unsoldered and dac works with no problem when J1 in shortcut. Probably stress on usb port will be much lower now.

According to my experience, this solves the issue of using separate usb cables for charging. It will suck all power if you connect it to a mobile device.You should keep the battery. Dac uses battery anyway.

There is a J1 marking nearby at bottom of the pcb.

Now, it is not waking up from sleep state in desktop dac mode. Playing with knob doesn't help. I have to plug off usb cable and wait until it turns off itself...

Well.. I was aware of that U1 has a "Desktop Mode" with J1 which is quite true. I doesn't go off when this jumper is in shortcut. I guess this is a valid reason for desktop usage. At least for me. Anyway, I think I found the cause of my problem. The PC that I connect U1 is a quite new, AMD...

U1 is not the only usb audio dac I use. This problem only happens with U1.