Audio device

An audio output device is where macOS sends sound: for example, the Mac's speakers, a monitor's speakers or a USB audio interface. The current or default output is the device selected for ordinary system playback. Each device supplies its own available volume and mute controls. Apple's Audio MIDI Setup guide Apple describes this arrangement

A device has a name you can recognize and a separate system identifier called a UID. BetterDisplay can use a name or UID to associate an audio device with a display for native volume control. That association tells BetterDisplay which device to control; it does not select the current macOS output or add volume controls that the device does not have.

Matching is also specific to the job. Native volume control, keyboard display targeting and feedback-sound routing use different rules. Volume Control explains these distinctions and the owning settings.

A multi-output device sends playback to several component devices. BetterDisplay can match that combined output for display-control purposes, but it does not create or configure the combined audio device for you.