Computerworld - https://www.computerworld.com/article/3290363/apple-ios/why-two-apple-homepods-really-are-better-than-one.html#tk.rss_all
Apple recently updated its HomePod software, introducing AirPlay 2 and support for stereo pairing. I’ve been using these features since they arrived, and this is what I think so far:
What are the improvements?
Apple’s iOS 11.4 update introduced HomePod 11.4 which bought two significant new features to HomePod systems: AirPlay 2 and stereo pairing support.
AirPlay 2 lets you control music playback around your home using Siri, HomePod and AirPlay 2 supporting speaker systems from third party manufacturers. So long as all your systems are on the same Wi-Fi network you get multi-room playback and controls.