I'm building the Soulsonic Hunny Bunny, and it works - it just seems to have a LOT of gain. I know that the Gain structure of a circuit is dependent on many factors - but would a simple way to reduce the output gain be to change the value of the Gain pot for the circuit - for example. the Hunny Bunny gain pot is 100k Lin, could I reduce it to 50 to limit the gain, or would I have to increase it?
I know I could just try it and see, but I don't want my ears to prejudice my findings. And I am trying to learn how the circuit components interact.
There is no general answer to how to modify an arbitrary circuit for more or less gain. You have to understand the circuit topology to see what your options are. Fortunately, circuits are generally composed of well-known building blocks stuck together. So you can just learn the building blocks. In other words, once you understand the non-inverting amplifier, go ahead and read the rest of that Wikipedia article. Then start reading about building blocks with bjts, fets, etc. Plenty of good articles on Wikipedia and elsewhere for those guys too. Maybe start here, and then follow the links to other articles.