I can give you a 'real life' example of using a mixer like that.
It would have been around '97-'98, i lived in a house full of muso's, this place had virtually no furniture outside of music&PA/Hi-Fi gear, most of which was half working, broken, of questionable origin or just plain crap. Anyway, had heaps of 'jams' that usually ended up in some half-arsed attempt to record some stuff, usually to tape but i had my already decrepit PentiumII with CubaseVST that i had set up to record with people laughing at me and saying things like you can't do s&*t like that on a computer.
Had a 4-channel radio shack 'Microphone' mixer a lot like yours but only one bank of four ins 1/4" or rca and two outputs, all unbalanced, i think it had a switch labeled stereo which routed 1&2 to L out 3&4 to R out. I used it to mic the 2 drum kits we had set up, all dynamics, probably Rolands or some other cheap stage mic, unbalanced usually through a xlr to 1/4" cable. I'd just use it to get a mono drum mix from 4 mics to record. The levels that came out of it were basically useless, i remember running it's output through a technics 1200 DJ mixer to get a signal anywhere near worth recording. Nobody worried about impedence matching or the fact we may have been using a RIAA eq'd Phono input to get to the preamp.
I also remember using it as a 'breakout box' to plug stuff into my pc. It's really just a passive summing mixer that someone thought slapping microphone on to it's name described it better, or just had no real idea what it is. Ive seen similar mixers used in live sound for a similar purpose, to balance mics before running into another mixer with a preamp, but I'm talking in bottom end situations - pub gigs, big parties,buskers.
But i guess the point of that 'back in my day' ramble was that as long as we could record something, quality didn't matter. We were mostly recording punk/thrash, with turntables and some jungle D&B splashed through it, the late 90's were bloody awful for people trying to fuse every type of music into some godawful fusion sound. There was no pretense of professionalism or finesse, we thought these raw sounds were better than any of the crap 'the system' was telling us to like, and we all thought we were pretty avant-garde and bucking it as hard as we could. We wanted our music to sound anti-social, so we were happy with the results. These days i think the results sounded like crap, mud under noise.
I think you've already had your question answered already by others, just thought you might relate to that as real life. I say use what you've got, you might be able to pull off a miracle, but accept your gear's limitations, and from what you said about where you are at in life, i'd focus on your music and finding your happiness in that, an impedance matched input, as good as it can sound, will never stir your being like beautiful music - there is no system, it's just a bunch of coincidences and events that we choose to define in our own minds, and none of us really have any idea at all about the truth. IMHO P.S. sorry about the long winded drivel, but i think you asked for it, and i was bored
it will be enough for that moped mixer.. 
