Rounding out Apple’s AirPlay 2 update trifecta is tvOS 11.4. The update adds support for AirPlay 2, and lets you use target speakers with your AirPlay setup.
AirPlay 2 supports speakers in multiple rooms, and Apple says compatible speakers are coming from Bang & Olufsen, Bluesound, Bose, Bowers & Wilkins, Denon, Libratone, Marantz, Marshall, Naim, Pioneer and Sonos.
With an Apple TV or AirPort Express you can use other speakers, too. You can, for example, play the same music on your HomePod, Apple TV speakers, and speakers connected to an AirPort Express in different rooms without any latency.
Apple TV updates install automatically, but you may have to wait a few days before that happens. To install the tvOS 11.4 update now launch the Settings app on your Apple TV and go to System > Software Updates.