For clean tones, I use the treble all the way up. For more distorted tones I roll the treble back. I also reduced C20 to the same value as C3 (22uf down to 4.7uf). Curious, what does C21 and C13 do? The higher gain mode has a much better treble response. I’d almost like to have the normal gain channel have the same EQ as the high gain channel, but without all the extra gain.