Voyager stereo with no sound
 

I have a 2001 Chrysler Voyager. The stereo has no sound, none at all, not even any hissing, the speakers are completley silent. The stereo works and finds stations etc just no sound. I have replaced the stereo with another branded unit which I know is fully working and still the same problem. This first happened when I took the original stereo out to see what the iso connector was as I intended to fit an after market unit. Any ideas please

would there be an ampliphier on a 2001 car, if so where would it be and would it have a fuse, or is there a relay for the speakers that may have gone?

https://youtu.be/Tcmdj9LQPdI