The IT-AS411 Series Audio Switchers are 4x1 audio switchers that have an extra mic/line level input for a voice lift system or direct microphone input. All models have four switched program audio inputs and an independent mic or line level input that is summed (mixed) with the selected active program audio. All models have balanced or unbalanced input and output capability. DIP switches are provided to set the voice input level to mic or line, adjust microphone sensitivity, set phantom power and select mono or stereo operation. They also have adjustable volume control buttons and mute for both the program audio and voice inputs.