Radio or Reciever???

[Rabid]

My radio just took a dive on me. It is stuck. Basically the clock stays on the same time, the station stays on the same station, all the settings are frozen. NO SOUND EITHER which is killing me. I was going to simply put another radio in but when I took the dash apart I found that the radio connects to a reciever underneath the dash. How do I know which one is broken??? I don't want to go buy another stock radio, go through all the trouble of replacing it and then find that it is the reciever. Any help is appreciated.