I have a 1989 Audi 100 with about 72K miles on it. The car still has the original am/fm cassette Blaupunkt deck in it. The speakers are original as well. The system works fine right now. I am aware that there is a stock booster \ amp installed under the rear seat.

I want to install a cd/mp3 player in the car. My question is, do I have remove the booster / amp from the audio system before I install the new deck or does it depend on the power output of the new deck? If so does anyone know how to bypass the booster / amp? Of course I should look at replacing the speakers as well.

Jamie

If you have the Bose sound system, there isn't an amp under the rear seat.

The only info I'm aware of regarding this amp, is for the avant. And I believe this was for the standard Audi sound system, not the Bose.

It is the sedan model.............When I put in the new battery last year I found the amp under the driver side rear seat................the car is completly stock.........

My advice to you is do not remove or play with what you think is an aux amp. The only electronic module in the left rear seat is your brake anti-lock module. Removing it can cause serious problems when trying to stop on ice or snow.

Get a bentley or Hayes manual and it will describe the function of this module.

Like audiqv8 said, this is your ABS module. Don't remove it, it has nothing to do woth your audio system. (unless someone upgraded your stereo system before)

You have amplifiers built in each one of the rear speakers. Amps are attached to the bottom of the speakers.
If you are going to install a new head unit and use the stock speakers, you must bypass these amps(both of them) OR i would suggest - get a new pair of decent rear speakers for much better sound.
Also, when installing the new head unit, don't forget to feed power to the antenna amplifier too or your radio reception will be bad. Follow the little wiring diagram attached to your old headunit and you'll figure out how to send power to the radio antenna amp.

How do i know all that? I have the same car and it had the same stock stereo before i replaced the whole audio system. I put new speakers in all corners and i also ran new speaker wiring. It's worth it.

If you have any more questions, feel free to ask.
Good luck!

...I collect spores, molds and fungus.

It would be a very bad thing.