I have a hole in the back panel of my 81 2204 an want to make use of it. Want to add a hot rod switch that will add bypass caps for the 2nd an 3rd gain stages. Id like to keep it clean inside and not mess with other soldering as the amp is almost 100% original minus the mic pre in hole. Idea of adding caps from the cathode socket pin to the switch and grounding there. Resistor grounds will be stock and be grounded to the pots. Do the cap/resistor need to be grounded together??