I'm wondering if someone can explain this circuit in terms I can understand. Here's a quote from the manual: "Variable Power is not like typical preamp overdrives. The. Variable Power circuit actually controls the cutout stage of the amp. When the Master Volume control is set low you will notice little or no change from the Variable Power control because you are asking the amp to give you very, little wattage. The higher you set the Master Volume control, the more you will notice the effect of Variable Power." I viewed the Joe Bonamassa vid with the SD engineer but still couldn't quite understand it. Any explanations are greatly appreciated!