sony dvd home theatre system dav-dz 150k amplifier hissing/ humming
sony dvd home theatre system dav-dz 150k amplifier hissing/ humming noise which is more than actual audio sound ,give solution
You didn’t say if you tried a different signal source or not, just to eliminate if it was the input signal that was the problem and not the amp.
Noise problems in audio circuits can sometimes be caused by a missing earth connection between the different boards so that effectively they are at different potentials or perhaps faulty filter capacitors on the supply rails to the audio amp ICs (not the main supply capacitors but on the supply rail at each audio amp IC).
Here’s the service manual for the amp.
It has the schematics so you may just have to start tracking down where the noise it starting from.