I dont want to lose the stock functionality of my stereo in my genesis so Im thinking a line out converter will work out well when I got to get an amp, subs, and a box. Since I wont be using RCA's (dont think the stock stereo has RCA outputs), how much quality in sound am I losing? Is it REALLY noticable, or just slightly, or will I not even really notice at all? Not entering any sound quality competitions. This is just for daily driving with an amp and subs to give me some boom.

 

In a word: lots> Noticeable usually but more so when compared to a system hooked up through a proper head unit. Gets the job done however and is a quick cheap way to do things, properly done its liveable.

 

A moving car is about the worst possible listening environment. Don't get absolute bottom-of-the-barrel junk and you might not know the difference.

 

buy a Kicker KV2, it's got line level inputs that go to RCA, you can use it as a low or highpass filter depending on where you take the sound from on the back of it. It's also powered so it doesn't take source power to feed it, lowering your electrical losses.