Infinity problems
 

I have a 2003 crysler town & country and the infinity stereo and cd player turns on and seem to work but no sound. I thought the stereo was bad so I took it in to a stereo shop and they put a new different stereo in. still no sound then they said the built in amp was bad I said ok now what and they told me each speaker has its own amp and must be replaced . How can all the speakers go bad at once? I said no thanks I didn't have time and left . DO i need a new infinty stereo to fix problem or something else?