Underground is way of saying I don't rap about vanity (cars, chains, and chicks). I'm Lot like Slug from Atmosphere a lot less like Lil-wayne from Cash Money Millionaires (remember that bullshit?)
That's the difference between Underground and Mainstream rap, lyrical content. Two separate genres if you ask me in a lot ways. (that's nowadays, to me all seems to start going down hill in the mid 90's with the explosion of gangsta rap)
Given that it was swiped from a live venue, the second-hand mic you own is fairly likely to actually be an SM58. It might actually be a decent microphone, so if you're still getting bad sound maybe the mic isn't the problem, perhaps it's how you're recording your voice?
Could be that
and the lack of mixing board. I run it straight into my pc using and 1/4 inch to 1/8 inch adapter.
Nasty I know, but it sort of works, sort of.
Could it also be the acoustics of my living room? OR possibly my sound card?
I've never had any complaints from my live shows, so as far as I know my Vocals are good, getting them recorded in a professional manner seems to be the hurdle. But that could even be me being a bit critical. I sometimes forget that I spends hours and hours listening to myself, so I can pick myself apart quiet easily, and quickly can get dissatisfied with quality.
I using a Midi keyboard for most everything else, that or samples I've bought and arranged using software. So I also don't have much experience with actual recording of anything. I wouldn't even know how to set up the microphone to pick up an instrument properly.