Unfortunately, audio quality is still poor. But you can install ViPER4Android. I found it pretty hard to make Viper work properly, so here is a mini guide:
1. Install Audio Modification Library and Audio Compatibility Patch through Magisk.
2. Install ViPER4Android FX through Magisk.
3. Reboot. Open Viper and install the audio driver.
4. Find the file "/data/adb/modules/ViPER4AndroidFX/post-fs-data.sh".
Add this code to the end of the file:
Code:
magiskpolicy --live 'allow audioserver audioserver_tmpfs file { read write execute }'
magiskpolicy --live 'allow audioserver system_file file { execmod }'
magiskpolicy --live 'allow mediaserver mediaserver_tmpfs file { read write execute }'
magiskpolicy --live 'allow mediaserver system_file file { execmod }'
magiskpolicy --live 'allow audioserver unlabeled file { read write execute open getattr }'
magiskpolicy --live 'allow hal_audio_default hal_audio_default process { execmem }'
magiskpolicy --live 'allow hal_audio_default hal_audio_default_tmpfs file { execute }'
magiskpolicy --live 'allow hal_audio_default audio_data_file dir { search }'
magiskpolicy --live 'allow app app_data_file file { execute_no_trans }'
magiskpolicy --live 'allow mtk_hal_audio mtk_hal_audio_tmpfs file { execute }'
5. Reboot. Now open Viper and enable Legacy mode. You are ready!
Disable any app equalizer (e.g. Spotify or Youtube Music equalizers).
For this solution I used this post
comment. If you know any better (and faster) way, please let me know.