Airplay not working

 tjohnson,

Thank you for the update.

Since you have already reinstalled the macOS, you will need to test your login items, to see whether software in your user account is causing the problem. To do this, you can create a new user in System Preferences > Users & Groups and creating a new admin user. Restart the iMac again and log in as the new user. More detailed instructions are in the link below. You also want to unplug all nonessential devices while performing this test.

Set up users, guests, and groups on Mac

If you're having the same issue with a different user, we'd recommend contacting the receiver manufacturer. Let them know which iMac and macOS you're using, and that you're trying to AirPlay directly to the receiver, so they can check it out.

When looking at the AirPlay system requirements article, and following the link for "Speakers and receivers with the label "Works with Apple AirPlay" > Receivers > "Yamaha RX-V Series" link > The Yamaha page does't list your "Yamaha RX-V58" receiver: Yamaha AV Receivers

Thank you for contacting Apple Support Communities.

 tjohnson,

Thank you for letting us know. Yes, you are right, when troubleshooting iTunes/Music that does have to be disabled at times.

If you see an error in Finder or iTunes on your computer

Happy Listening!

Thank you for contacting Apple Support Communities.

Hello and welcome to Apple Support Communities  tjohnson,

Thank you for contacting us regarding AirPlay on your iMac. You have come to the right place and we are happy to assist in getting this resolved for you.  Although we are not experts in troubleshooting the stereo systems, we would suggest it may be a compatibility issue with BigSur. We would recommend updating the drivers for the Yamaha. If this doesn't resolve the issue, please let us know so we can assist further.

Thank you for contacting Apple Support Communities.