JBL MSC1 Monitor System Controller with RMC(TM) Room Mode Correction Master Volume Control A/B Speaker Select A/B/C input Source Select Subwoofer Output with Level Control and High Frequency Speaker EQ Headphone Output with Volume Control Mute Control RMC On/Bypass Control RMC Calibration MicrophoneMSC1 Control Center Software Selectable Cross Over Frequencies Adjustable Low Frequency