I have a M-Audio M-Track MKII (USB) and I bought a pair of Behringer studio monitors recently and using 1/4 TRS cables between them. I hear permanent noise of the cpu on the monitors, even it changes with the movements of mouse. I was using studio headphones till now and never encountered this.
Btw I use 6 socket power outlet which an UPS is connected to it and my pc is connected to the UPS. The monitors are also plugged to one of the sockets on this outlet.
How can I overcome this issue?