I mean, I don't know that much myself, but 5 tubes? I don't know how all that works, but I know how my amp works. It has 4 preamp tubes. V1- input stage (effects all 3 channels) V2- Channel 2 and 3's gain stage, V3- Half drives the active eq and the other half drives the effects loop, V4- phase inverter.

I also have a 3 channel tube preamp that uses 4 tubes in a similar way (minus the phase inverter). IIRC (LATS you may have to correct me on this) V1- input stage, V2- channel 2 & 3's gain stage, V3- drives the active eq, V4- buffer for the effects loop.

I'm am very interested in knowing how you plan to use 5 tubes in a single channel preamp with no tone controls.

Why don't you start off with a distortion pedal with 2 tubes. 1 being the input driver and the other being the gain stage?