The Mackie Big Knob Passive monitor controller provides switching between two sets of inputs and two sets of studio monitor speakers. Passive circuitry means your audio signal will remain true to its source, while a large volume knob makes it easy to make level adjustments while you're mixing. Handy buttons for Mono, Mute and Dim put necessary monitoring functions at your fingertips. The original Big Knob has been a popular solution at Sweetwater for years, and with upgraded circuitry and a streamlined control set, the Mackie Big Knob Passive is an ideal monitor controller for project studios.