Sounds like there are problems in the digital section. This is usually non-repairable and it's probably best to junk it. Though, you could try giving Emotiva a call to see if they still support this. They would have to replace the entire digital board, which is basically the entire HT processing, digital and DAC board, so I'm not sure if it's worth the cost.
It's possible that the speakers could be damaged if your digital section decides to fail badly and outputs an extreme static to your speakers.
You could try an external amp, but I suspect you would have the same problems. However, that is a total assumption and I could be wrong.