The overall master gain can be adjusted by the buttons labelled "+" and "-". Each push will increment or decrement the gain by 1 dB. The maximum master gain is +20 dB, the minimum is -80 dB.

The master gain setting is stored permanently and restored after a power-cycle.

The Master Mute button displays the current mute state. Pushing the button inverses this state, thus, the complete unit can be muted.

The master mute state is not stored permanently. After a power-cycle, the device comes up unmuted again.