As the name suggests, the Mackie Big Knob Passive is a passive monitor controller and can therefore be operated without a power supply. Two input sources can be routed to two outputs as required. The signal can be switched to mono, dimmed and muted via one button each. The volume can be continuously adjusted using the classic Big Knob.

This is really a sturdy hard made solid device and is exactly what you need to expand your studio, cost effectiveness is slightly expensive but its as i said a solid device and it fits right in in my studio, just what i needed thanks mackie
Does exactly what is says on the box. Makes monitoring a whole lot easier, doesn't affect signal path at all and piece of cake to install and operate. A winner !