Have loud humming that has appeared from my DAV-FR1. I know it's an old system, and I don't use the DVD/CD player, but it's worked fine for about 7 years and I'd like to keep it (was quite a job wiring the room through the walls and under the floor). Had the hum a few times in the past, but it always went away after about 20 minutes of warm-up. The hum gets louder as the volume increases. Any fixes? If not, are there any receivers that use the same wiring?