Afrite

Hi,
I have an Audi A4B6. The car had only front speakers and a third speaker in the center of the dashboard (i don't know how they call it). It's a nonebose system. i couldn't find any amp in the car so i think there's no factory amp pre-installed. The speakers plug contains only 4 wires for the front speakers. How the center speaker is connected, i don't know! The radio unit was a third-party unit (no audi symphony...). A few months ago i've installed an Audi RNS-E navi system. Now I want to install rear speakers but the RNS-E has only a 2 channels internal amp. The only way to get this done is to connect an external amp to the line-outs of the RNS-E. Now i've made a decision not to use the internal amp of the RNS-E and connect everthing to an external amp. Which amp do i have to use (i'm not using a subwoofer, need only some good sound inside of the car) and how is the center speaker connected as i can't find any wires for it's connection?
Any help will be appreciated.

TwentyValveB5+S4

you don't need it. it's only a good idea if you've got some sort of surround processing, like a Dolby Digital decoder or 5-channel stereo-capable processor.

that's what I'd do.

B5S4_Oz

I've found speaker wire between the speakers and amp does the trick...