Would be nice to know what it is.
Cool, like I said, I was guessing. So you can adjust the B+ for different amounts of dirt/gain, pretty cool. Is this a custom design of yours or something that is on the market?
I didn't follow your last sentence though, not sure what you were trying to say about Gus G and a SFX-01???
wonder why the input impedance is so low. very cool about the adjustable B+
But, what is it?? Give us a make/model!?!