The step by step I used to get it working was as follows:
- Flash a SELinux permissive magisk module - reboot
- Install ainur narsil magisk module - reboot
- Disable ainur narsil in magisk manager (not sure if this does anything but it works for me)
- Install Audio Modification Library - reboot
- Install Viper4Android magisk module AND open the app and install the driver (will reboot as a part of this)
- Install Audio Compatibility Patch magisk module - reboot
- Re-Enable ainur narsil module in magisk manager
- Remove SELinux permissive
I've had success in this order. for the Audio Compatibility Patch I use vol up for the first two options and then vol down for the rest.
The app also seems to need to run in compatibility mode or legacy mode
Not sure if this will work for everyone but seems to be a bit hit or miss in general