The mixer is the central place for audio routing in EventSoundControl. All modules of EventSoundControl (which have audio output) are shown here as sources. The sources can be routed to the outputs which are configured also here.
You can add as much hardware in- and outputs to the mixer as you have hardware installed or use dummy output drivers for streaming and recording.
All sources an outputs are displayed as individual channels where you can set volume level or the balance. ALso VST plugins can be added to a channel here on Windows and MacOS systems.