As the CXN (V2) includes Chromecast Built-in this will allow you to add the CXN (V2) to a Cast speaker group. Once added you will be able to Cast audio to multiple speakers at the same time.
To add the CXN (V2) to a Cast speaker group please follow the instructions below:
1. Ensure all Cast speakers and CXN (V2) are on the same network.
2. Download the Google Home app from the App Store (iOS device) or the Play Store (Android device).
3. Once download you should find all available Cast speakers on your network. The app will break these down to show speakers you have assigned to a particular room and also list all unassigned speakers as 'Local devices'.
Google Home Homepage
4. To setup a speaker group select the 'Add' button along the top of the screen and choose 'Create speaker group'.
5. Next, choose the devices you want to add to your new speaker group.
'Choose devices' screen
6. Next, you will need to give the group a name.
'Create name' Screen
7. Once created a new section 'Groups' will appear on the main screen. This will list all groups and show you how many speakers are included in the group.
'Groups' section on Home screen
8. To beginning casting to your group; you should find the group name in the cast playback devices within your music streaming app.
9. Once casting to the group clicking on the group icon within Google Home will provide you with playback controls.
'Group' playback controls.
This screen will display the currently playing track and the app being Cast from.
The blue circle in the middle of the screen gives you overall volume control over all speakers within that group. The button in the middle of the screen will enable you to play/pause the currently playing track.
Below this is the track progress bar. At the bottom of the page are options to 'Stop casting' and open the app that is currently being used.
10. clicking the slider button in the top left of the screen will allow you to control the volume of the individual devices within the speaker group.
Additional speaker group settings.