In my experience yes I have heard an improved sound from an aftermarket PC on a CDP in my system. When I heard this was with a MAC (My Audio Cables) HC Sound Pipe power cord installed on an Emotiva ERC-1 CDP. This was with budget gear so people's mileage may vary. When I moved the MAC HC Sound Pipe power cord to my 1st generation PS3 I believe I got an improved picture and SQ but at the time of that change I made wholesale changes power cord wise and power conditioning wise in my system. So yes I believe a PC can improve the sound of your CDP but again trial and error may be required with potentially more expensive power cords or with different wiring types.
Best of luck.
Best of luck.