snap, crackle, pop go my speakers

[davidpertuz at mindspring.com]

Drove the G20 to Detroit this weekend and on the drive back yesterday my audio system was driving me crazy. (Crazy, I tell you.) Every so often the system will snap/crackle/pop loudly. This tends to come and go, and is infrequent enough that I've lived with it for a couple of years, but it was afflicting me for the better part of 5 hours yesterday so the aggravation can get high when it does come around. 

Noise is independent of audio source (CD or radio) and volume adjustment - all that is needed is that the system be on. Yesterday it was affecting the sound volume too (low volume) though it usually doesn't. All four speakers affected equally. 

The sum of the above observations tells me that it is either the amps or connections to or from the amps. I did notice that possible one of my rear shelf speakers had a partly separated cone (?) but disconnecting it produced no change and it is implausible that I have 4 bad speakers, but only 5%of the time. 

If it's connectors, I don't think I know where to look. If it's the amp(s), is this anything that i can fix (I can solder, etc.) or need I just go to a parts yard and find another pair? Or is it something else. The total number of annoying little things wrong with the car is high enough now that I'm going to use my day off next week to try to fix most of them.

thanks,
David