The Auxiliary Return (Aux Return) is an input channel on a mixing console dedicated to receiving the signal from an external effects processor.

It's the return port for the audio you sent out of the mixer to be processed.

The signal flow works like this:

1. Aux Send: You send a copy of the signal from one or more channels to an external effect (such as reverb or delay) through an output called Aux Send (Aux Send).

2. Processing: The external equipment processes the signal (adds reverb, for example).

3. Aux Return: The processed signal ("wet") returns from the effect to the mixer through the Aux Return, where it is mixed with the original signal ("dry").

The channels of Aux Returns are generally simpler than normal input channels, often lacking an equalizer or offering fewer send options, as their sole function is to control the overall volume of the effect being fed back into the main mix.