Figured it out. I was able to make a cheap RFI shield (two layers of tin foil....) and the Mp3 player worked right next to the mopeds engine.. I should be able to get the AMP to work by doing the same thing.
When I took the tin-foil off the Mp3 player with the moped running, it stopped instantly... when I put the tinfoil between it and the moped, it worked fine.
I am a little concerned about the extra heat the tin foil might cause... I may line the whole pannier with foil instead of just insulating the AMP.
I'm glad-- I've been trying to figure this out for about 2 weeks. I decided to research the EMI shielding industry-- the professionals use foil attached to a polymer in layers-- this is the most common way, because it addresses the "Victim" of the EMI without addressing the cause. it would be impossible to wrap my whole moped engine in foil to stop EMI/EMR output, so I need to block the "victim" (amp) from the EMI.
Why is this post important to people who don't have a stereo? Someday you might try to listen to a walkman on your ped, and unless you remember the tin-foil EMI shield, you may not be able to have music-- the gears will turn but the output will be disrupted.
I'll post more when I have the new 80watt amp insulated and working.