460 sub help

ok.....i have a stock mach 460 sound system in my 98 gt.....i want to add a preamped aiwa sub just to make a lil more bass cause im not a stereo freak......but i only have one single wire coming out of the back of the preamped aiwa as an rca cable.......what do i do?....(i know im have to get the signal from the amps but u need positive a negative and i only have one rca wire outr of the back)
 
You need to buy an 12 or 10 guage amp wireing kit.
12vold lead from battery with inline fuse. 12 volt remote (16-18gauge) tapped into a power source that only turns on with car. and a ground you need to make in your trunk. Now for the signal i dunno, i would buy a line converter and tap into your two rear speakers to get the rca signal you need. But im not too familar with the Mach's setup. but there will be no positive and neg right in the trunk for you to hook up, you need to run these your self.