Almarg has commented on this subject before, but since I'm no EE, I'll try to explain why the digital signal should be kept separate from the analogue components.
As I understand it, some of the electrical noise generated by a digital component can be fed back into it's power cord, then thru the wiring of a power strip or any other device it is plugged into, eventually reaching the system. That is why some power strips or power conditioners have a digital only input; to isolate that signal. I assume that a digital PC is designed to capture and isolate any feedback of digital noise.
As I said, I've learned a lot from the experts on the forum, so feel free to add to my explanation. Whether or not the noise is audible is system and listener dependent.
As I understand it, some of the electrical noise generated by a digital component can be fed back into it's power cord, then thru the wiring of a power strip or any other device it is plugged into, eventually reaching the system. That is why some power strips or power conditioners have a digital only input; to isolate that signal. I assume that a digital PC is designed to capture and isolate any feedback of digital noise.
As I said, I've learned a lot from the experts on the forum, so feel free to add to my explanation. Whether or not the noise is audible is system and listener dependent.