I was reading back over some old post and found a thread started by @jsnwhite619 where we discussed reducing grid stopper values and decided I’d give it a shot. Since I was planning to redo the inputs on this amp to eliminate a ground loop that was bugging my OCD, I picked a 5f11 as the victim. In some of the Valve Wizard writings he suggest going as low as 10k and adding a cap between 100pF and 470pF between the grid and ground. He also goes into the maths regarding Miller Capacitance with a formula to calculate the actual outcome with a given tube. Using the 3 inputs of the 5f11, I mounted some 27k’s at the jacks and a length of shielded cable from their juncture to pin 2 at V1, with a 120 pF silver mica cap from there to a ground lug at the tube socket. I decided on those values only because those were some of the choices I had on hand in my parts bin. I didn’t work out the formula since I knew I wasn’t going as low as 10k. The outcome: Well, first off, getting rid of the ground loop reduced the noise some more on an already quiet amp. Secondly, there seems to be no added RF or microphonic noise in the input circuit. Sound wise, I’m getting a volume level at around 5 that I was getting up around 8 on the volume pot, so mission accomplished, I think.