iOS 11.4 is going to be available on iTunes soon, possibly with tvOS 11.4, macOS 10.13.5, and watchOS 4.3.1, with nearly two months of beta testing. An associated software update for HomePod will also be possible through the Home app.
The software will allow multi-room audio with HomePods and Apple TVs. Another AirPlay 2 authorized speakers while becoming available, adding the Sonos One, Playbase, and Play:5. And also designs from Bang & Olufsen, Bluesound, Bose, Bowers & Wilkins, Denon, Libratone, Marantz, Marshall, Naim, and Pioneer.
The Multi-room audio feature allows the users to play music in any room, from any room and transfer music from one place to another. Or even can play the repeated song throughout using an iOS device, HomePod, Apple TV, or by commanding Siri.
AirPlay 2 is also going to allow stereo pairing of various HomePods. Working with spatial awareness to see or sense their position in the room. Every HomePod automatically synchronizes with the audio to sound as ideal as possible.
Playback and volume controls of AirPlay 2 are available on iOS within each app and in Control Center. On iOS 11.4, additionally users can also ask Siri to perform music in any room, a collection of rooms, or everywhere in the home.