https://www.theverge.com/2018/5/29/17406664/homepod-apple-stereo-pair-multi-room-audio-music-airplay-2-ios-11-update-how-to

iOS 11.4 is here, and it brings with it a few highly anticipated features for Apple’s HomePod speaker, including the ability to create a stereo pair of two HomePods and support for Apple’s new multi-room AirPlay 2 standard. Here’s how to get everything all set up:

Before you get to the fun part, you’ll have to first make sure everything has been updated to iOS 11.4. To update your phone, you’ll need to head over to the Settings app → General → Software Update. As for the HomePod, it should automatically look for and install the update at midnight, but you can check that it’s been updated or force the install yourself by heading over to the Home app. There, you’ll be able to see if there’s a HomePod update available, download and install the update, and manage other features for your HomePod. And in a neat option, the Home app can automatically detect if you’ve got multiple HomePods, and download and install the update for all of them in one shot.