Check the simple stuff first
Is it muted?
Is the source selected sending signal (radio staion broadcasting, cd playing, ipod all the way ect)
Try doing some basic troubleshooting like,
see if all sources available yield the same result (TV, Radio, CD, Ipod, Aux jack)
When you turn the volume all the way up, do you hear an audible hiss from the speakers?(or use a test tone) If so, your amp is working and the problem is, your unit is not sending any signal to it.
If possible hook up your speakers to another system to rule them out, however I doubt that is your problem.
Here is sony's recommendation and a review video
Let me know what you get
SONY eSupport How to troubleshoot if there is no sound or intermittent...
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