ok so here is the problem: i have a randall valve dynamic rh300 head which is 4ohms going into my marshal cab which is 8ohms (i know its not correct thanks) and its making a horrible high pitched squeeling noise the only time it does it is when my sonic stomp is connected. i dont understand why..... its hooked up correctly. i can controll the squeel with the level controlls on my fx loop but doing that lowers the volume on my amp. is my sonic stomp dead or dying? or is it my amp? help please!