Thanks for the replies, I have talked with a couple of techs ;ocally and none of them really seem to know much about the electronics of the hybrid which I found hard to believe with them being techs. Now the resistors you mentioned to change Eddie? Have you had any problems out of the amp since you changed them? I do fine with simple cap and diode and resistor changes but building circuit boards I have zero luck with and as much as I would like to build the presence control I best leave that alone,,lol.