EE is not my forte. Although this little circuit is so simple that I could get myself 90 percent there, it performs such an important function that I would like to get it more like 99 percent correct. I want to add the circuit to this board http://www.ebay.com/itm/Finished-bo...plifier-board-subwoofer-output-/251210310744? I already fried one board. Another is on order and I'm "bench testing" it with a number of SMPS ranging from email@example.com to firstname.lastname@example.org. Below is the source of the protection circuit I want to add. Is it possible to calculate the correct value/capacity for diode/resistor/pmos fet from the description I've given of the power sources and amplifier used?