Rich's Tongfamily (Richtong.net add-on)

Wow, this is actually pretty incredible, but with macOS Monterey, you can route audio to *any* Airplay device, it appears to know how to make Airplay 1 devices like an old Apple TV 3rd generation play multiple audio, so when you go to Apple Music and choose the radio icon at the upper left, you will see that all audio devices now have a checkbox after their names. This used to require a third-party utility called Airfoil from Rogue Amoeba.

You can select as many as you want and it syncs audio across all of them. I had been using a third party application to do.

In addition, you can now use MacOS Monterey as an audio destination as well, so if you can use your really good MacBook speakers as well. What’s a good use case for this:

1. You are in isolation from COVID and have a HomePod mini, MacBook Pro M1 and an Apple TV 3rd generation. Now you can play music from your Mac to all these sources and fill the room with music. Pretty neat.
2. I will say this stuff is definitely flakey. That is when I first tried this, it worked with the HomePod Mini, but not with the Apple TV. But I did a reboot of both and it seems to work.
3. It is really nice to be able to set the audio levels for each source and it does a great job of millisecond synchronization.
4. Finally, this means that when you say to Siri, ‘Play music everywhere’ with a little twiddling you can really make it everywhere.
5. One interesting note is that it does not seem to work with their Radio souirces that is when I try to do with Apple One, it only plays on the MacBook, so there is some sort of bug or maybe licensing issue. But it does seem to work with Apple Music library playlists.