
When Sonos introduced the new Sonos One back in October, the company confirmed it would add AirPlay 2 support to Sonos speakers later in 2018.
At the time, Sonos did not specify which of its devices would support the new protocol, but Sonos has offered some clarification in the form of a new blog post that includes AirPlay 2 details.

According to Sonos, native AirPlay 2 support will be available on the Playbase, the newest version of the Play:5, and the Sonos One.
Older Sonos speakers will not support AirPlay 2 on their own due to processor limitations, but they can be paired with the Playbase, the Play:5, or the Sonos One to enable AirPlay 2 functionality. A Sonos Play:1 grouped with a Sonos One, for example, will support AirPlay 2.
Apple thus far has not released AirPlay 2, despite the fact that it was first introduced as a feature of iOS 11 back in June of 2017. AirPlay 2 functionality was initially included in iOS 11.3 and tvOS 11.3 betas, but it was pulled ahead of the release of those updates.The computing platforms and software architecture in some of the older Sonos players like Play:3 and Play:1 simply don't have the horsepower to support AirPlay 2. The original Play:1, for example, has about 1/16th the processing power of its modern equivalent, the Sonos One. But by taking advantage of newer Sonos hardware, we're able to make AirPlay 2 funtionality available throughout the house on speakers old and new.
AirPlay 2 functionality is now included in iOS 11.4 and tvOS 11.4, but it is not yet clear if the features will be included in the final version of the software.
Article Link: Sonos One, Playbase, and Play:5 Will Support AirPlay 2 Functionality