Ian,

In my wish list there is that Supertriode and the variable damping PCF/NCF control (like the old Bogen DO30A).
Unfortunately as a technical/commercial guy, I'm often abroad all week long, and there's no more time for experiments...

If you want to, I can share with you how I'd do an amp like the one your friend wants (I've done something similar in the past for a 7 string dropped guitar player, with two PA: a 100W all tube and a 200W class D with independent volumes).

Back on topic!