The RDL RM-MP12A is a rack-mountable 12-channel audio monitor panel. Each of the 12 inputs can be individually calibrated for unbalanced, balanced, 8 ohm speaker, or constant voltage speaker lines. Each input has its own pushbutton, which selects that input for monitoring via the calibrated meter, internal speaker, headphone output, and/or an optional external speaker. A mix mode is also available, allowing you to mix multiple sources.