after market stereo; wiring for amp?

[FD'93-525iT]

I just bought an Alpine CD w/ FM/AM and the sound from the rear speakers is not what is was with the original unit. I was told at one stereo shop that the amp in the back would need to be wired into the new system. Anyone have any direction on what needs to be done? thanks

[Mr. BILL]

What year? Any E34 '91 and newer you can buy a harness adapter. You connect the white wire, (It's the car amp) to the power antenna lead on the harness. I think it's light blue. That's it, shouldn't take more than 10-15 minutes.

[andyman32]

I used this:

http://www.bmwe34.net/e34main/upgrade/stereo_wiring.htm

It was dead on. Good luck!