Aux-send

An aux-send (auxiliary send) is an electronic signal-routing output used on multi-channel sound mixing consoles used in recording and broadcasting settings and on PA system amplifier-mixers used in music concerts.

The signal from the auxiliary send is often routed through outboard audio processing effects units (e.g., reverb, digital delay, compression, etc.)

A post-fader output is used in order to prevent channels whose faders are at zero gain from "contaminating" the effects-return loop with hiss and hum.

A benefit of using an aux-send is that it enables the signals from multiple channels on a mixing console to be simultaneously routed to a single outboard device.

Musicians whose voices are barely present in the "front-of-house" mix, such as backup vocalists, can have their sound clearly and loudly sent through a monitor speaker so that they can hear themselves singing and ensure that their pitch and timing is correct.