We know that we know.
Yes they are resistive "potentiometers", but they don't "gain" anything.
-0db is no loss of input voltage and -Infinity basically means 100% loss of input voltage.
To me "gain" means: the ability to take something and make it louder. Which they don't\can't do.
Amplifiers have a fixed gain, and input attentuators, and fancier amps (like the FP's) have input sensitivity adjustment;
and fancier amplifiers still, such as the crowns, inukes, powersoft etc have onboard DSP that have true "static gain" adjustment in the software(only), and often input sensitivity adjustment and load monitoring and EQ, limiters (and a bunch of other junk) in the software too.
I like calling them what they are: input attentuators, that way the noobs don't get confused as to their purpose/function. hehe!
The master volume knob and trims and level-sliders on your AVR/preamp/mixing-board are true "gains" or level controls (at least as far as the external-facing implementation it is...), they boost and output more voltage that what went in.
"gain structure optimization" I'll let pass, because their isn't a better phrase for it.
The goal of that being: to be able to output max-power without early-clipping any inputs or outputs in the system (digital and analog inclusive).
Often it is a battle between:
"how loud can the system get without electrically clipping"
"how many acoustical db's can the system safely generate"
"how loud does the user actually desire/want it to be"
"a realistic/achievable/tolerable average(or maximum) SPL level with say 20db of dynamics headroom i.e. standard THX calibration / recording studio mixing standards".
Which are 4 entirely-different things and often inter-competing things.
A 20db swing takes a lot of horses, that's a 100x increase in power (beyond the average-level) without clipping or melting or bottoming out.
Few systems can actually achieve that, and that's just THX-level, not even factoring in a hot or aggressive playback level yet.
It is problem I've been terrorized with for years. It took like 32 subwoofers and 100kW of FP amplification to have sufficient headroom to meet the demands I was desiring/placing on the system. 16 subs and 8 "normal" pro-amplifiers simply wasn't enough.
I could still use another 5 24's and another 2 FP20k's to fill in the <20hz.