The La Grange pedal is designed to emulate the famous British "Plexi" amplifiers from the mid 60's. The wide variety of controls and switches, give you decades of legendary plexi tones, all the way up to the era of the modded amps from the late 80's and throughout the 90's.
An independent boost function, with a level control, can be activated via it's own foot-switch to be either used as a stand alone boost, or together with the La Grange's main circuitry. Essentially two independent pedals, with the boost being in series after the La Grange!
Reinhold designed the La Grange pedal with an op-amp input, followed by five discrete Class A gain stages and incorporated Germanium diode clipping. This approach minimizes the input noise floor while retaining touch sensitivity and clarity throughout the entire gain range.
Original FSB thread and schematic available here.
The schematic should be correct but it hasn't being verified yet.
You can find the original manual PDF here.
I've used Mark's Dual Effect Offboard wiring.