I would like to finally upgrade my stereo to an amplifier after enjoying speakers for a few years. I have a 2007 RTL and bought a Blaupunkt PNP amp that plugs inline with the head unit to use existing wires for speakers, after reading the fun people have had with the door connections, something I wanted at the time. I did a search and know that 5 yrs ago when I got this was somewhere here, but now can't find it. I believe there are outboard amps in the RTL which renders my amp useless. Is this true? Thanks.