Audio Systems: Buzz noise in 93 camry speakers, pioneer cd player, amp converter

Question
Hello,

I recently attempted to install a new Pioneer cd player in my 93 camry xle. I bought the wiring harness and hooked up all the wires, and when I powered the cd player up, there was a buzzing noise in the speakers. I can hear the music just fine, but even with the music turned down all the way there continues to be buzzing. I know my car has a factory amplifier under the passenger seat, and the cd player has a built in amp as well. Do I need to somehow bypass the factory amp to get rid of this noise?  

Answer
What you have run into is impedance mismatch. It causes signal path ground loops and makes all kinds of noise issues
Some solutions are to get an OEM amp converter.
Scosche makes a nice one; Part#: OEA4
http://www.scosche.com/scosche_caraudio.aspx?CategoryID=229&ItemID=OEA4

Or, you could make a bypass harness that would remove the factory amp from the system. Some suppliers make the bypass harnesses, but you may end up making your own. It's possible, but lots of work.