Its usually the simple pedals that give the best effects, so heres the Electro-Harmonix Signal Pad explained.

This pedal acts as your guitars volume knob allowing you to switch between different preset volumes, for example leaving your amp on full blown overdrive but using passive attenuator to bring the level down for a clean break, then kicking it off and back into the crunch! By placing this in a different order within your effects chain, you can experiment with different combinations to enhance your sound, and it can also be used as a lead boost, pretty snazzy if you ask us.

True bypass
Turn any single channel amp into a two channel setup
Switch from lead to rhythm on the fly
Use in front or after any effects to change the tone of that effect
Battery Powered LED / Optional US96DC-200BI power supply