A, B, A+B, & C, D, CD's Knutz! WTF!?

[ATX.WeenR 5]

Ok once again don't jump on the gimp ass crippled old dude for not understanding a term or wtf-ever you consider this but I recently was seeking an active crossover with the possibility of getting an eq/line driver too since there are such beasts out there in 2018 so I scoured the web's, and the internet's too... I even looked around when I would go into someplace that sells car audio and after weighing my options I did something totally off the wall and bought a Stetsom STX2448 "Digital Audio Processor." I figured: 'Hey I get all of that, plus a parametric EQ and I can configure the xover any whichaway I feel like, PLUS I get to have my first unit that offers time alignment (or so I thought) and it all comes packaged in a box I cannot even read (because the writing isn't in American it's in Brazillion) all the way from Brazil (hence the no speaky Texican) for just over a hundred bucks! Where's the catch right?! Except for the fact that I can't read the user's manual, but you have to play give and take sometimes! I mean how many different spellings are there for "big-ass-subwoofer" are there in the world?! 

All right all kidding sside. This is where I stopped smelling what they're stepping upon. And this is likely where some douche is gonna want to be like "duh and s+#t dude blah blah blah yakkity yakkity...." Which I stop listening to those and go right into death threats and stuff usually so... N/m.  Ok so the fuggin thing has two inputs (sucks right? Not necessarily, I'm cool with it)  so there's the standard red and white rim on the RCA's so you'd think R & L right?! But above them are the labels "A" & "B" while the outputs are labeled "1, 2, 3 & 4" giving me room for 8 CHANNELS in the classic sense of the word in car audio terms. 

So I go through configuring this thing on it's little 15x2 character onboard, blue-backlit, LCD screen and I get to a point where, ACTUALLY THE ONLY POINT where I'm a little confused.. especially considering it's made in Brazil and I don't even speak Swahili! It's got a section called routing and the options are: (you ready for this shit?) A, B, AAAAAND.... A+B... Three options. But with it labeled a and b over the left and right input I'm thinking of it like right and left and mono. Which doesn't seem right but at first that's all I can think being that there's red and white RCA in's... 

I mean are there a bunch of music files anymore or at all really that are mixed to a 4 speaker front and rear surround setup? I think in the seventies they had some BS called like umm.. 'quadrasound' or 'surrounspec' or some dumb, hardly marketable name like that. The only other thing I could come up with was either a subwoofer signal in A and a mids/highs or full range signal in B... OR.... Like some units for home use that are made with respect to separate listening areas with an A,B switcher OR just like any universal A, B switch TWO TOTALLY DIFFERENT AND UNIQUE SIGNALS ALL TOGETHER (which sounds totally in left field but at this point makes as much sense as any of the options)

So if you haven't figured it out yet... WTF ARE THE A AND B INPUTS? HOE ARE THEY DIFFERENT? is it just left and right and like a mono mix for subwoofer purposes or what? I've searched from Google's welcome mat all the way to their nasty arse back alley for this answer and it's only confused me more...

Taramps has a unit almost identical and I read that manual too and neither one says anything more than basically: "plug in RCA's to inputs A & B and then yada yada blah blah....." This units crossover is super badass and the eq's are top notch. I do have a beef with the delay function but that's another wordy-ass thread that nobody will read! 

WHAT THE HELL IS A & B? the unit is super user friendly, in fact I could have set it all up with no manual.... Except for this part.. ROUTING... so what is it!!?????

Thanks in advance for being cool and friendly and helping me without making yourself a mortal enemy!

Regards

Edited November 27, 2018 by ATX.WeenR
Add pic

[ATX.WeenR 5]

Checking back to see if any feathers were ruffled. Glad to see it's all quiet in here. Sorry guys I was at work on a break so I was trying to stretch the funk out of it. I tend to get wordy when I'm stalling.