I have browsed around the forum and Google and come up with an idea that I need verifying. I have the Concert II Head unit (below) and I want to install my vibe sub (built in amp on the top) in the boot. I believe the front speakers in the Audi are powered by the head unit while the rear and standard sub are powered by a biscuit sized amp in the back. I have also found out that the small amp's signal is sent from the head unit using a line connection. If this is the case can i tap into that line signal using these: If I do this can I still have the rear speakers working as well as the vibe sub? Split the line signal? Obviously I would disconnect the standard sub. I hopefully want to then tap into the amps remote connection and send that to the sub. Then finally run a power cable through the firewall (which I have found the grommet for already). Has anyone attempted this? Will this work? Iâve found this guide by AndyMac: http://freepdfhosting.com/6b28e2fdcb.pdf. Itâs for the Bose system which I donât have but it does mention at the bottom about the half amped system.