[B 4 You]

As everyone else said, you just hook all those wires to the (+), (-), left and right of your rear speakers. Your rear speakers' volume, quality, etc. will not change at all, so you don't have to worry about that. But remember, if you fade the volume away from the back, it will lower the volume of your subwoofer. The same goes is you adjust the bass on your head unit, you have no choice with the stock stereo but to adjust the levels to your sub as well. It does work, it does sound okay, but you don't have very many options unless you have gain and bass control directly on your amp. I have that same line-output converter, and I haven't had a problem with it yet.