Noise Filter

[wallyghs]

I need to make a homemade noise filter for my amps. When the engine is running (stock electronic igniton slant), I get a buzzing from my 6x9s(powered by an MTX thunder) and my subs(Cali Bass). Both amps were used POSes, but cheap! I have 6 guage wire running from the battery + to the back to a distribution block with 10 guage running to each amp. Neither are high wattage. I have a question though. What would be the best way to get the negative. Right now I have it just chassis grounded in the trunk. Would I be better off using the 6 guage to the negative battery terminal back to the distribution block and just avoid chassis grounding?

Also... I have a strange problem with my pioneer headunit. When in CD or tuner there is no noise but when I insert an MP3 cd (any mp3) there is a humming that comes from the 6x9s(on the head units front output... rear is to the subs). The rear output does not have this noise, nor do the front speakers(that I can tell, they're 3.5" rockfords). This is really annoying since I bought the best stinkin 6x9s I could(the yellow pioneers). I have a really horrid memory and its too cold to go out to the car and check model numbers, else I would. Any ideas on getting rid of this noise? my wiring form the headunit back is pretty cruddy, I have fairly good quality RCA patch cable(s) going back. The (s) is the problem in that there is a cable extender in between the two cables. I just used gold plated female-female extendors. Could this be the problem? I'm using the same for the subs but no noise that i can notice.

Umm.. let's see... I think that's it. Thanks!