Boss SD-1 Mosfet mod vs stock (danish intro)

sammenligning mellem SD-1 wampler Mosfet Mod vs stock
Introduction in Danish

[diegoambrosio]

Very cool! The change made the sound way better! QUESTION: Would it be possible to use a vacuum tube (12au7, for instance) instead of the MOSFET? That would be awesome! I believe some architectural modification would be required in order for the tube to fit. Nevertheless, in terms of circuitry, would it be possible?