What is the difference between the two?
> Airplay doesn't offer multi-room audio; AirPlay 2 does
> AirPlay lets you stream from any Apple device to your speakers or TV
> AirPlay 2 lets you play from speakers over Wi-Fi, and it'll stay in sync
> AirPlay 2 lets play different songs in different rooms with multiple HomePods
Personally I've been very happy using AirPlay 2 with recent iPhones, a collection of HomePod Minis, an AppleTV and Denon Receiver. It makes it pretty easy to set up complex audio routing configurations from your phone. You can send a stream to several devices simultaneously while controlling volume independently and as a group. You can see what's playing on each device. Audio quality is good, battery impact seems fine.
I wish I could have strong AirPlay 2 support from non-Apple devices, but I know how the ecosystem works. Still, easy enough to use something like the Emby iOS app [1] to bridge arbitrary content into the system.
[0] https://www.pocket-lint.com/speakers/news/apple/144646-apple...
That seems strange. Because I remember buying several used Airport Express base station to build a multi-room audio system. It worked great. That was around 2006/7, if my memory serves me right. At that time the protocol and the feature was called AirTunes.
Previously I believe AirPlay (1) had a fixed 2 second delay, which was not a great UX and also caused issues in syncing multi-room (or multi-output) audio.
AirPlay 2 does this in a much more dynamic way that reduces the latency (anecdotally, maybe 100-200ms is typical) and improves the sync. I have no idea how it achieves this though.
Edit: OP actually has a really nice breakdown. https://github.com/FD-/RPiPlay#airplay-protocol-versions