Haha...yeah, that can be confusing.
Alright, here's how it goes:
"Kick In" refers to the
microphone that is placed on the inside of the kick drum, usually a boundary
microphone of sorts, or maybe an
omnidirectional lavalier that can handle the extreme SPL.
Shure's Beta91 is an example.
"Kick Out" refers to a second
microphone, placed next to the resonant head of the kick drum. These are the "kick drum mics" that you see advertised and sold at many stores.
Shure's Beta52, AKG's D112, and Audix's D6 are common examples. You may want to try flipping the
POLARITY (not
phase) on this
channel. Every other
microphone covering the drumkit is having positive pressure applied to its
diaphragm from the sound generated by hitting the batter head of the drum. Thus, the other microphones are flexing the opposite direction that the kick drum mic's
diaphragm is when it is used on the resonant head. This
polarity flip keeps the whole kit in
polarity and can lead to a more full kit sound.
Let your ears be your guide - if it sounds good, it IS good. Oh, and don't spend a lot of time getting the kick "just right". No one's there to hear the kick drum - they want the whole kit or band or whatever.
Sometimes, when there is no hole in the resonant head of the kick drum (and there is not much chance of bleed from other parts of the kit or nearby instruments) you can place a mic by the batter head. It can be annoying for the drummer and you, as placement is pretty important.
Before any EQ is applied, I would work with mic placement - move the "Kick In" mic closer to the batter head for more "slap" or "click" or, my preferred word, "attack". Move it further away for less "attack". The "Kick Out" mic can be adjusted similarly.
It should be noted that the two mics are usually blended and not used independently, so that they combine to achieve the desired kick drum sound.
Happy experimenting!
P.S. - for some more fun, you can sidechain a signal generator into a
gate that is opened by the kick drum. Set the generator's frequency at 40Hz and get ready for the rumble or around 62Hz for some thumpage! Adjust and blend to taste...it helps, of course, if your
system has that low-frequency extension. If you have aux-fed subs, even better.
Now then, look up some of these terms and learn some more!!!