The AVR will also adjust what it sends to the sub internally once you run the room correction software with the microphone
and this is where you can tell if you need to turn that knob up or down, based on what results Audyssey gives. If it sets your sub 'trim' levels very low, like -12. that tells you the gain knob is turned up too high (it's trying to turn it down)... if it goes very high, like +12. your setting is too low (it's trying to turn it up). You ideally want to see a setting between +3 to -3... 0 being spot on.
mods, can we have a 'dislike' button ?