The ESI MoCo Passive Monitor Controller not only attenuates volume, but provides input and output switching to different monitor sets. Two sets of inputs can be sent to either of two sets of outputs (no balanced to unbalanced conversion). This way, your audio interface's balanced output can be sent to one of two sets of monitors, or select a secondary audio source to be output via either of those monitors. The front panel contains the large central knob, which drives a high-quality volume potentiometer, input and output selection buttons, plus an L/R switch and mono mixdown buttons.