Stereo wiring colours

Hi!

I just bought my first Audi ever and I'm struggling to find the information I'm looking for in forums.

It's an Audi B6 2004, with the Bose speakersystem. If I understand the information I've found correctly, it's the fully amplified system. Two black connectors at the back of the stereo. That are supposed to be there at least, because this is where my issue lies - the previous owner for some reason sold the car with no stereo, and with the wires cut off too close to the connectors to be able to connect them back. So instead of bothering with solving that, I figured I´d just install an aftermarket one I have lying around. But I cannot for the life of me find any kind of diagram that tells me what color belongs to which speaker etc, to connect the new cables. None of the diagrams I´ve found, with just the numbers of pins on the different connectors, look like the ones I have in front of me when I'm sitting in my car. If anyone could help me out with this, it would be insanely appreciated....