THIS IS IT! I rotated the transformer per your suggestion and hum is gone!
There is only slightest noise that I can only hear with my ear right next to the tweeter and only if the room is quiet.
The board in top right corner is not soft start but remote trigger and 12V for the switch LED. The switch is also wired with 12 VDC that turns on relay coil and passes 120 VAC trough contacts.
Thanks Again to everyone. Great suggestions. I tried most of them and you collectively solved another conundrum.
Thanks Ben Mah.
is your problem 60Hz or 120Hz?
60Hz is what your transformer radiates and once you have rotated it if that would have gone then the best way is to use a shield on the transformer keep all the mains radiated fields in it.
If its 120Hz then thats real pain altogether even Im facing it only after connecting the two inputs. I strongly feel that there should be super thick 6sqmm wire to be looped to all grounds to get extremely low resistance and develop any potential across any ground points.
