https://forum.xda-developers.com/galaxy-s20/accessories/s20-low-volume-ess9280-9281c-based-t4080285
When I use USB DAC using the new ESS 9280/9281C chipset USB audio dongles, the volume on the earphones come out too low even at max volume on s20 ultra. The same dongles and earphones sound tested with Note 9 running android 10, and windows 10 computers, sound output levels were correct.
When connected to S20ultra, sound volume is less than half of what it should be compared to when using note 9 on android 10 or windows machines.
Tested USB dongles where this happened:
Hilidac Atom Pro ESS9281C Pro
Zorloo Ztello ESS9281C Pro
And generic ESS9280 DAC earphones.
Other USB dongles tested do not have the problem:
Meizu HD
Musiland MU2-HP/MU3
Sonata HD
Seems the S20ULTRA is detecting wrong max volume when a ESS 9280 series DAC is connected.
maybe s20 has a bug for Ess chip.
Zorloo Ztella has updated the firmware to fix the problem.
One interesting fact is that overwriting the Ztella firmware on the Atom Pro fixes the problem.
if you have atom pro typeC version，you can upgrade firmware from our website.
The firmware of version 0411 on your website did not solve my Atom Pro, and the improved firmware of Zorloo Ztella solved my Atom Pro.
You must know and solve this problem.
It is a bug that occurs on all Samsung smartphones starting with the Note 10 series. This is a clear bug.
I am Korean and there are many people in the Korean web community who complain of the same problem.
https://drive.google.com/file/d/1nHeqbmsAnSg8t2uJe47XqiJ9mw9bdTfj/view?usp=sharing
Here is the Zorloo Ztella firmware.
After applying the Zorloo Ztella firmware, if you test it, it will make a difference.
you can download our lastestd version firmware from our site.