The OUTPUT MENU is a brand-new section available in Manifest user interface.
From there you can manage the volume control of any Volumio device available on your local network and switch between each of them, you can create Multiroom groups, output your music to Sonos and Chromecast devices or listen any Volumio music source in local.
You can also directly go to the PLAYBACK MENU and manage the general audio settings.
Here a video overview:
https://www.loom.com/share/a12706d500b84f118b8419c3cfc2685b