[G6ONEDave]

Looking at the pics in thread 17, the amplifier pcb appears to have a bridge rectifier on it, so why is there also what appears to be a bridge rectifier circuit on the pcb seen below the transformer in your first pic?

You only need one bridge rectifier for this build unless there is something else attached somewhere that is not showing in the pics. I would suggest the removal of the pcb below the transformer and the voltage regulator. Then take the transformer output to the bridge rectifier that is on the amplifier pcb.

Something else to check is if the amp chip is stereo or mono. If the amp chip is a stereo type then both inputs will need a signal and both outputs will need speakers to be attached. If there is only one input of a stereo amplifier circuit being given a signal then the other channel could be picking up interference that would produce noise in that channels output.

Dave