"Hi, thanks for your help so far. I have performed the above but am still getting no audio out, with the exception being for about 1 minute after I quit coreaudiod. Are there any other steps to try? Cheers"
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Getting No Audio:
A. Boot in Safe Mode:
While booted in Safe Mode, Login Items do not open at login, and system files can be fixed. How to boot into Save Mode depend on your device: Start up your Mac in Safe Mode - Apple Support
B. Single-Out this User:
Create a new Administrator user, seeing if your still get this issue when you log into it. If not, then it is an issue pertaining to your current user. If so, then it is an issue with the entire macOS.
C. Getting Instal a macOS After Migration:
A. Reinstall the macOS:
It seems your macOS is now corrupt. So, try reinstalling the macOS, seeing if all completes. Go Here: How to Reinstall macOS from macOS Recovery - Apple Supprot
D. Reinstall the macOS:
If nothing above works, then your should backup your Mac, and then reinstall the macOS. Nothing would be lost; it's just that missing system files and corrupt system files, will be reloaded and replaced, respectively.
IMPORTANT: Create a Backup First: Be sure you back up your Mac with Time Machine, prior to performing any major change, such as this reinstall. That way you will have something to restore your Mac from, should anything go wrong afterwards.