Audio Upgrade in E53 X5.

[jaykay]

hi guys
i need to upgrade my sound system in my x5 2001 model. i want to add 2 amps, 1 x 4 channel for the door speakers
and 1 x 1 channel/ 2 channel bridgeable for the sub.
i have already had the box made from specs i got from an older thread.
Ive figured out that my system is non dsp and maybe that it actually doesnt have an amp as i thought coz on another thread i read that says those which have a mid and 6 speakers have no amp. so my questions are:-

1. If i dont have the amp whats the black thingie at the left rear compartment under my shuttle.
2. How do i tap into the audio signal to supply my amps and where do i get the speaker wires if theyre not on that black thingie
3. i dont want to have to run new wires to the doors and would want to use the factory speaker wires. How do i accomplish that?