Why don’t the volume/gain controls work on my amplifier?

If your amplifier is equipped with an RS-232 input (for connecting a wall mounted control panel), there is also an ON/OFF switch for this feature. When switched to the ON position, the amplifier disables the volume/gain controls on the amplifier. If you do not need to use the RS-232 input, then ensure the switch is in the OFF position to enable the function of the control knobs.