After announcing the feature last month, Google is now rolling out an update to Chromecast users that allows them to add their devices to a speaker group in order to play music across multiple sources. All generations of Chromecast are supported by this feature. This comes after smart displays were added to the list of supported multi-room audio gadgets.
According to users, in order to take advantage of multi-room audio with a Chromecast right now, you’ll need to opt into the device’s preview program by going to the Chromecast settings section of the Google Home app. Afterward, the update should arrive on your Chromecast. For others who don’t want to opt into the preview program, there’s a good chance you’ll get the update in the coming weeks.