Need some help with replacing the stock amp

[Excellent30]

I posted this to the Radio Wiring and Amp Bypass thread with no luck:

Hello everyone, I have a 1988 325i Convertible with tweeters and a stock amp in the back. After installing a new head unit, the sound does not work past a certain (medium) volume due to the amp. I purchased a cheap 4 channel amp to replace the stock one instead of running new wires all around. When I cut the amp harness in the back, I noticed that there was only 16 wires. I do not know which ones belong to which speaker because this assortment of colors does not match any guides I have read. They are:

One that's all white (power?)
One that's all brown (ground?)
Black/White
3x Black/Brown
Grey/White
Grey/Brown
Red/Grey
Red/White
Yellow/Red
Yellow/Black
Blue/Black
Blue/Brown
Violet/Grey
Violet/Black

Any help is highly appreciated, I have been trying to figure this out for a while.
Thank you

[StereoInstaller1]

First, unwrap some harness so you can tell which are pairs, that should help

[Excellent30]

Thank you very much for replying, it kind of made my day. haha

I unwrapped the harness and did not find any pairs. What do you suggest I do from here?

http://imgur.com/R6ejNsL