It is more likely to be an output stage problem. The unit will be shutting down as a result if a DC offset in a faulty channel. You will need to isolate the problem somewhat to diagnose what is going on. Do you have a multimeter and a decent knowledge of electronics? If so, then I can talk you throiugh some things to check. If you dont think you are up to it, I would take it to a HiFi repair guy for a look.
It may be more worth your while to buy a refurbished unit here
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