Why complicate things unnecessarily?
There’s no such thing as a “sound good” knob. You could buy an amp with a three band tone control setup, but that isn’t always better. The great thing about a simple tone control is that it doesn’t destroy the signal the way that complicated tone stacks sometimes do. The Fat Dog tone circuit is of the treble-cut variety, meaning that your bass is always there, and the knob controls how much treble there is.