I'm not a 100% sure but think some kind of compression would help. You could use a software like Audacity where you would just import the file and export it as an mp3 with a bitrate of around 192kbps. You could also use an online converter like this: https://convertio.co/wav-mp3/. If it still sounds scratchy you should probably lower the bitrate and try ...
Answered my own question with help from this link
from Mark Hills
Once you have bluealsa working and can connect devices and play, then these additional steps open up dmix capability and allow audio mixing.
Install loop module once only.
Edit /etc/asound.conf for each bluetooth connection - i.e. if you change device, update this file.
Try running sudo apt purge pulseaudio and rebooting. It can sometimes cause problems with audio output.
If it's not installed, try running sudo apt install pulseaudio which ironically can also fix things.