[Radio Wrangler]

I'm not sure what that circuit would do. Your final triode is a cathode follower configuration giving no voltage gain so the loop gain has to be below unity, and no inversion. So with positive feedback it isn't really the usual Baxandall circuit. The amount of boost is not going to be much at all.

Watch out for DC on your bypass path versus whatever the tone control network floats at. I'd expect operating the bypass switch to create a loud noise.

David