With my amplifier sony TA V902 I don't have sound out from any source.

When you amplifier is powered on if the speakers are powered on and you hear that the output is switch on then it is possible that the fault of the amplifier is in the preamplifier.Open the set and check on the input of the amplifier with a signal . If there is output the fact is confirmed of the preamp stage. Now we have to confirm if the fault is in the source swtiching or the preamp equaliser/ tone section. Using a good signal tester and hoping that you are familiar to handle the electronics inside, the IC can be identified and changed. Use extreme care and test at low output, Use a help of an expert to signal trace the fault. Hope I could help. Good day