aftermarket radio not playing sound anymore

I just purchased a radio from a local custom radio shop. Wired it up in my 91 b2200, and it played music great. The truck had aftermarket speakers already and they sounded good too. About a week later the radio still worked... But no sound is played through the speakers... Any ideas of what It could be

Are you running the speakers directly off the HU or through an amplifier?

Sorry to take so long to reply.... Had a long week. But its fixed! Was a wire shorting out in one of the speakers.