The Audio Destination Node outputs audio to your system (or to the output file when exporting). Simply put, what you connect to it is what you hear. It’s a simple, but fundamental Node for every project to produce audio output.
Simply put, the audio signal connected to this input is what you’ll hear during playback, as well as in the output file when exporting.
Note, that some Nodes can produce an audio output even without playback (an active audio signal is indicated by a glowing blue connection). The Audio Input Node is one obvious example. When such a Node is connected to the Audio Destination Node, the signal will be audible in your system output even without playback. This is because the Audio Destination Node simply forwards its input to the system output.
The system output device to use during playback. Defaults to your default system audio output device.
Except for the default system output option, this setting will remember your selection, even if the selected output device becomes unavailable. When the output device becomes available again, the Audio Destination Node will automatically use it.
For the default system output option, whatever the current default output is will be used.
Multiple Audio Destination Nodes can be used in a single project, in which case audio signals are simply added together (assuming the same output device is set). This is the same as if an Add Audio/Control Node was used before a single Audio Destination Node.
It’s technically possible to connect control signals to an Audio Destination Node, but it’s unlikely to yield any reasonable results besides random clicking, depending on the signal.