The CMC4 gives you the control of your sub woofer. Once a balance is set between the main speakers and the sub woofer the main level control will control both. There's also a mute switch to check your mix with or without the sub.
Four balanced stereo inputs on XLR's
Three balanced stereo outputs on XLR's
Main level feeds main speaker output
Sub level feedss sub woofer output
Sub output has level control and mute switch
Fixed level, feeds meters or cue system