I have a VT20+, and I've been doing a little bit of digging, but I'm confused over how the amp's 4 volume controls and tone controls model the original amps.

For example, the Cali Clean Special models a 1957 Tweed Twin. That amp has Volume, Treble, Bass and Presence.

I understand that if I set the middle of my VT20+ to 12 o'clock, it will take it out of the tonestack, modelling the Tweed's tonestack. So far so good, but what do the VT20+'s Gain, Volume, and Master Volume map to on the Tweed? And does the Tweed's Presence control map to anything on the VT20+?

Any advice would be welcome.