Fair enough. What I mean is: a balanced (differential) shielded cable is a reasonable way to transmit an analog audio signal — common mode noise can be rejected pretty well, as can currents that might be induced in the shield due to a ground loop.
With RCA, you have none of these benefits. Heck, with RCA stereo, unless one end is isolated or you cut one of the shields, you cannot avoid a ground loop — the stereo connection by itself contains a ground loop.
back when I was a stage tech I always carried a bunch of isolating transformers with me. Cost 5 bucks on ebay and save your ass when dealing with obscure loops.
With RCA, you have none of these benefits. Heck, with RCA stereo, unless one end is isolated or you cut one of the shields, you cannot avoid a ground loop — the stereo connection by itself contains a ground loop.