Great studio monitor controller. Used in a smoke-free studio and kept in good condition. Thanks for your interest! No power supply included

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.