99 RL: no sound from RL

I've got a 1999 Acura RL. About two weeks ago, the sound from the radio would cut out. It would go away for 10-15 minutes and then return. The sound could last for hours. However, now the radio produces no sound at all. The buttons work fine including the changer but absolutely no sound. Any idea what could be the problem. I checked the fuse in the driver's panel and also the fuse under the trunk, but both were fine.

I don't know if this is relevant but the SRS light came on a while back and it was taken to the Acura dealer for repair. Any chance they could have knocked something loose or damaged something.