Miraculously, the radio came back to life after I removed the left rear speaker:
While checking the wires and everything, I noticed that the left rear speaker
sounds much weaker than the right rear one. I unplugged it, and all the garbling
and noise disappeared. The radio/CD/tape now plays fine on the front speakers.

I thought that it was the left rear speaker that caused the problem, so I had it
checked at a local car audio store, and they confirmed that it was fried. I
bought a replacement pair of rear speakers and thought that my problem was
solved. However, when I connected the new speaker to the left rear channel, no
sound came out (the old rear right speaker still plays fine). While attaching
the new speaker, I noticed little sparks when the wires touched the connectors
on the speaker. So, there must be some current going through the wires, however
the channel is silent. I wonder if the channel in the amplifier is bad after
all, and fried the old speaker initially.

Any suggestions how to diagnose this or determine if the radio/amp is at fault?

Any help greatly appreciated. Please respond to the group. Thanks!

AS