Given parts and a schematic, why not? That said, the Dumble was apparently designed with the studio and stage demands of the era, so Alexander Dumble either used a 50w and 100w design almost exclusively. Almost, because SRV's Steel String Singer is apparently 150w.
It can be argued that most of the tone happens in the preamp as the power stage is essentially a clean Fender style design, with the exception of that phase inverter balancing trim pot. But I have a feeling that scaling the power section down to 20w will inevitably have a different character to it.
BTW, learned all of this from ampgarage.com, and the people there are knowledgable and very helpful.
Sent from my iPhone using Tapatalk
