
Gain plug-in in MainStage
Gain amplifies (or reduces) the signal by a specific decibel amount. It is very useful for quick level adjustments when you work with automated tracks during post-processing—for example, when you have inserted an effect that doesn’t have its own gain control, or when you want to change the level of a track for a remix version.
To add Gain to your concert, choose Utility > Gain in a channel strip Audio Effect plug-in menu. See Add and remove plug-ins in MainStage.

Gain plug-in parameters
Gain knob and field: Set the amount of gain.
Phase Invert Left/Right buttons: Invert the phase of the left and right channels, respectively.
Inverting phase is useful for dealing with time alignment problems, particularly those caused by simultaneous recording with multiple microphones. When you invert the phase of a signal heard in isolation, it sounds identical to the original. When the signal is heard in conjunction with other signals, however, phase inversion may have an audible effect. For example, if you place microphones above and below a snare drum, inverting the phase of either microphone can improve (or ruin) the sound. As always, rely on your ears.
Balance knob and field: Adjust the balance of the incoming signal between the left and right channels.
Swap L/R button: Swap the left and right output channels. Swapping occurs after the Balance parameter in the signal path. The Swap L/R button is disabled when the Mono button is turned on.
Mono button: Output the summed mono signal on both the left and right channels.
Note: The Gain plug-in is available in mono, mono to stereo, and stereo instances. Only one Phase Invert button is available in mono and mono to stereo modes. In mono mode, the Balance, Swap L/R, and Mono parameters are also disabled.