Man, it is hard to squeeze v4a into Android q.
But the process described works.
First, uninstall all v4a and audio modification installed. Reboot.
1.V4afx magisk module. Not the apk.
2. Open the app, choose cancel to not install the driver.
3. Install audio modification library in magisk. Do not reboot.
4. Open v4a app and grant SU permissions, install drivers, it will reboot.
5. When booted, open magisk and disable audio modification library. (do not uninstall, just disable)
6. Open the v4a app, install drivers again, and it will reboot.
If it works, it works, This could work, depending on oem. I had to do
7. Open magisk, enable audio modification library.
8. Open v4a, install drivers, reboot.
Just trying to write a simple step by step.
Viper4android is God's gift to your ears.
I have a xiaomi MI 9 / android q / miui global 11.0.2