23. AUX INPUT - This Aux input is for the use of a Mp3 player. Input volume will be controlled by the channel two fader. 24. Channel Gain Control - This adjustment is used to adjust an audio source signal input gain for a channel. Never use the gain control to adjust output volume. Setting the gain level properly will ensure a clean output signal. To properly set the gain level controls: 1. Be sure the Master Volume Con- trol (33) is set to level 4. 2. Set the Channel Fader (27) to level 8. 3. B