Stream your music to multiple Chromecast devices, such as all the rooms upstairs or the whole house.
Lets show you how...
Using the Google Home app go into Devices, you should see all the chromecast devices on your network.
Tap the menu icon on one of your devices and choose Create Group.
Select the Chromecasts devices you want in the group and give it a name and tap Save.
Now under Devices you have your devices and your groups.
In MusicStreamer your new group will appears as a Chromecast device.