The Coleman Audio 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.

The Features
-Four balanced stereo inputs on XLR's
-Three balanced stereo outputs on XLR's
-Main level feeds main speaker output
-Sub level feeds sub woofer output
-Sub output has level control and mute switch
-Fixed level, feeds meters or cue system