High pitched noise from speakers with no input device

[drewdave124]

There is a constant high-pitched sound coming from the speakers which just started happening for no apparent reason. The sound gets quieter as I turn the volume UP. It also becomes dampened when I come closer to the system, which leads me to believe it's a clear EMI issue. Is there any way to fix this? Prefer advise of electrical/audio engineers, thank you

 

[Ralston18]

Not a feedback loop? Any cameras with microphones on your system?

If EMI try a couple of knots in the cables or a couple of ferrite chokes.

 

[Pete778]

could be the amplifier oscillating or the power supply coil whining