Hey RG, my understanding of the mods is to increase distortion (partly by increasing gain/vol in parts of the tube circuit). There's the overall gain structure (between various components (in the MP1 (preamp) circuits and other gadgets in the audio chain), which need to match BTW), and also the gain within each bit/component/circuit (so the gain mods are more about the MP1 tube circuit I think). So in MP1/2 you have 2 twin triode tubes, each triode is a gain stage and is driven by what comes before it, increasing what comes before it in some cases (if you turn it up
) causes clipping of the wave/signal, the nice thing about tubes is when you do that to any of the triodes, it produces predominantly even harmonic distortion (which us Guit players like
), took many years to develop SS circuits that came near to this sound/characteristic (and I would argue they're not here yet LOL).
So don't despair, the mods (particularly 3TM (i.e. 2 more triodes to drive hard!!)) are to increase gain in the tube stages and thus add more distortion/clipping