After a lot of designing, redesigning, scrapping and discovery of things I didn't know existed, the plan morphed into:
An all-in-one guitar amplifier based on the legendary Marshall 2204.
This was to be controllable by a touch screen.
It was to have space for twenty presets.
It was to have midi capability.
It was to have a zero loss effects loop.
It was to be programmable using an android app.
Ok, so I'm a Canadian living in America and as a result I can speak both British English and American English. For those not familiar in the US, a valve we actually call a tube here. Hee hee hee. Hope this helps. I"ll leave the discussion of tube theory ie low voltage plate design for someone else to comment. Great project by the way. Keep the pictures and narrative coming.