I have two Oppo players... BDP 83; DV 980H; both use a standard 15 A IEC connection and migratory cord.
Swapping out the OEM cord can sure change things.
I have the 80. It uses the standard IEC 3 prong cord, not the C7. The cord will not matter in this circumstance, it will be the difference in players. If you use the HDMI output from the Oppo, it is very highly rated. I don't know if it will be better than the Sony on your display but the type of cord will not determine the difference between the two.