it is coming from the router. When it is unplugged it there is no interference but no difference when the phone is unplugged. I hear the radio if that helps any also. Which port would be best? I only have firewire, usb, and mini displayport. So with adapters I can use HDMI though display port and thunderbolt using my firewire port. I dont know which are optical though. Also any suggestions on a reasonably priced DAC.