My husband and I just purchased a used Subaru wagon with an after market Radio/ CD player. Its an Alpine COA-7893. This is the first stereo we've ever had like this, and we don't have a user manual for it, though we've been able to find one online. For the first few days it was great. We were able to figure it out enough to listen to the radio, CD's, etc. A few days ago my husband was driving along, went to turn up the volume on the stereo and all the music just stopped. The radio and CD player are still playing - we can see it on the display. Everything seems to function normally, except there's no sound. Its like its on mute. (And yes, we have tried the mute button.) We've tried all the settings, even the reset button. We checked the fuses and they look good too. Any thoughts? Thank you!