You do have to log in. Here's what it says. He doesn't say he's running the subwoofer off the head using RCAs. What he's saying is his stock head doesn't have line level outputs so he ran speaker wire to RCA plugs to the amp's input. I've done it before. It's not ideal but it can work as long as you keep the gain down.
My sub is making an odd noise?
My sub is making an odd noise, it only does it on the mid to higher bass notes, the deep bass sounds fantastic. It sounds like something is loose or hitting the cone, but everything is good. Its a 10 inch Kicker CVR in a sealed box. It only does it on notes that arent very deep. Im running it with a namebrand amp (so i know its not clipping), and the amp pushes out enough power. I do have a stock headunit however and im running the amp via rca jacks that split into speaker connections(came with amp). If it matters im running it at 2 ohms and its DVC.