I've had a Marshall 1974x for about 4 years. As long as I've had it, I could hear radio on the tremolo channel whenever the footswitch is plugged in. The RF vanishes if I unplugged the footswitch. This would only happen when I play the amp in certain locations, including my house. For a few years, I never really bothered using the normal channel, but I've just started to recently, and I really like it! The only problem is that whenever I plug a cable into the normal channel input jack, I get RF on that channel too. See here for schematic of this amp: http://www.thetubestore.com/lib/the...Marshall/Marshall-18-Watt-Schem-Schematic.pdf I'd like to eliminate this whole RF problem. The conventional wisdom seems to be one of two things: 1) Solder a 50pf cap from the tip to the sleeve/ground of the input jack. This essentially creates a low-pass filter to get rid of the RF OR 2) Disconnect the wire from each input to the first tube grid it encounters. Solder a 68k resistor from that wire to the grid, in series. Option 1 sounds like less work, but which option has less impact on the tone of the amp? Would option 1 make the amp sound dark? Would option 2 lower the gain of the normal channel? Or are they both negligible impacts on tone? Also, would either option 1 or 2 also work for if I tried it out on the the input jack for the tremolo footswitch?