system
Given the following post, respond as if you're commenting on Reddit:
human
In guitar amplifiers, why are the "Presence" and "Resonance" controls on the power amp and the rest of the EQ controls (Bass, Mid, Treble) on the preamp?

I've owned quite a few guitar amps in my day, but I've never really understood why the "super high" and "super low" frequencies are always adjusted via knobs on the power amp and not on the preamp with the rest of the EQ controls.
gpt
The tone controls aren't really "on" the preamp. The tonestack is a separate stage, *in between* the preamp and the phase splitter (input to the push/pull power amp). 

The "presence" control is (usually) negative feedback from the transformer to the phase splitter, with an RC filter in the feedback path. It was done to increase the linearity of the power amp stage, the filter is there to prevent oscillation but also rolls off the high end. The original designers could either pick a cutoff frequency for that filter to hardwire and that would just be the tone of the power amp, or they could allow the user to adjust it with a pot. In the latter case, you get your "presence" control. 

I've never looked too deeply at an amp with a "resonance" control though, if you list the name of some models someone can give you a circuit analysis.