Are you sure? Some cables look like they are just merely speaker cables
with
RCA ends, but usually they are shielded cables.
My Phoenix Gold cables look that way but they are shielded.
But if they are indeed speaker wire with RCA ends I would replace them.

I wouldn't. The RCAs are about the last thing to check if you've got whine.
And even then, it's almost always that they're faulty.