So much can be added here.
* Ran across this article on Reverb on about Guitar Amp Attenuators. Not only a useful and interesting article, but demo guy plays ZZ Top's Getting On The Bus which helped me figure out some 7th chords in the tune that I've been struggling with other wise.
* https://www.mojotone.com/Mojotone-British-800-Style-Amplifier-Kit_2 - thinking about another amp build. Man, not cheap.