Help!I'maRock!
Mediocringly Derivative
"A modified Bassman® tone stack" is marketing BS. Don't expect a cathode-followed 5F6a Tweed or 6G6b Blonde preamp circuit or a tap off the Treble pot. Tone stack means the pots and the caps that connect them. All they want to do is invoke the Bassman.
What you are going to get is a couple of cap swaps, and maybe a different cathode-bypass cap on one stage.
i expect it to be a SF Bassman tone stack. i don't think it'll be a tweed or blonde thing. regardless, it won't sound like a Bassman anyway.
who wanted more gain out of a SFDR though? isn't that what pedals are for?