i have a 2003 a6 3.0 with "audi symphony" . . . i think all of the speakers on on the doors. i took some pictures of the speakers if that would help .. . and the head unit's output diagram . .

My head unit it broken and i want to install a car pc ...

what im asking of your guys is .. what kind of amp am i looking for here .. . money is tight and i am pleased with the stock speakers and how they sounded before, but head that an amp would make it sound even better ..