Re: p-rails ultimate wiring
When I think of “ultimate” I think of a handful of useful tones and a switching system that allows you to quickly change tones, not necessarily combining every possible tone by utilizing a bunch of switches.
That said, the easiest way to get individual control of series/north/parallel/south is with a pair of double pole rotary switches. The mini toggle could then be used as a “neck on in series”. That limits the number of volume/tone, though, and requires you use master volume and master tone, which is a deal breaker for some players. I know there are diagrams showing how to wire up the rotary switches somewhere on the forum, just a search away.