Hey folks hope you can help me out. I have a 2016 smart car. Previous owner installed new door speakers that sound nice. It had only those speakers. I installed two 4” scoche speakers in the rear. They helped alot. As far as I can tell the factory stereo only has a left and right output, so I tapped the tears into those. Sound nice. Now I am trying to install a 8” boss cxx8 600 watt subwoofer and a Cardual 600 watt 2 channel mofset amp. So I tapped into left and right rears and ran those into a LOC. I’m using a television DVD player wiring to connect LOC to amp. Ran power to amp from fusebox to fuse that powers off with key. Good ground. Jumped REM to power in on amp. Amp shuts off with key. Amp has protection feature that lights blue when good and red when not. It’s blue. Wired subwoofer two amp. Tried bridging, connecting to left channel alone then right channel alone, then both. Not a peep out of the subwoofer. I have been working on this for days now. It is wired exactly as any diagram that I have searched with the exception of the way I have the amp powered up. I can run power to battery and REM to back of stereo but I don’t see how that is the issue as it powers up fine. I’m a first timer with this subwoofer stuff. I used to wire the old Jensen 6x9’s when I was kid. No amps. Could it be the free RCA cable I’m using? At my wits end. Please any help greatly appreciated.