On my rescue roadster my audio system is OEM stock. The radio will play for a while (say 10 - 45 minutes or so) then the sound will cut out completely. Radio is still "on" and functioning but no sound. When I turn the system off for a while it will come back on and work for some time and then the sound will cut out completely again. I've installed two different OEM amplifiers thinking the problem was with the amplifier. I still have exactly the same problem. Any thoughts as to where I can look to solve this problem?