why do you have to mess with the cigarette lighter?
I want to do the same also. I thought I would have to put a live power feed from the battery to the boot for the amp, earth the amp to the chassis. connect the on/off cable that goes from the amp to the stereo, and connect the RCA from the amp the the stereo.
Then connect the amp to the sub, switch on and enjoy.
What I dont get is, I wan to keep the oem head unit, but theres an amp in the glovebox that I've got to get round.
What do I do now?