I have this oscilating high-pitched whining noise (see attached) when my amp is plugged in to the line-out on my computer (using a shield 3.5mm to RCA cable) . This happens even when the computer is off. I've tried two different motherboards but exactly the same noise. If I plug the amp in to anything else (eg, my phone) it's fine and no whining noise. The odd thing is I've even used an external USB DAC plugged in to the computer and feeding the amp with the analogue signal, thinking that would decouple the amp from the computer and any interference but I still get the same noise.
Does anyone know what might be causing the noise?
Does anyone know what might be causing the noise?