I think we need to be a bit careful here when talking about directionality of cables.
Some most definitely are and measurably so. Not all cables are built with the same wire and screen configuration.
Plain wire interconnects DNM Reson for example.
Two equally spaced conductors, one signal wire and one ground wire both connected at plug. Directionality shouldn’t be an issue with this type.
Coax style cables.
These have a centre conductor for signal and often use the shield for ground. Signal and ground (Shield) connected at both ends.
A lot is going to depend on how the RCA sockets are connected at each end and the connected components ability to filter out noise. But, I would be surprised if directionality was an issue.
My feeling with this type of cable is due to the ground/screen conductor having a much larger surface area than the signal conductor wire any RF noise the cable picks up, (that’s what the screen is for, it stops RF reaching the signal/centre conductor) may be introduced into the system; probably not an issue for balanced input/output components if balanced input has a transformer.
Separate signal conductors (one signal hot and one ground cold) plus screen.
These tend to come in three configurations.
Unbalanced.
Signal and ground conductors connected at both ends, screen not connected to plugs at either end.
I can’t see why these should be directional.
Semi Balanced.
Signal and ground conductors connected at both ends and screen connected at one end only.
These most definitely are directional. Whether the directionality is audible is another matter.
Any noise the screen picks up is grounded at one end of the cable. It is generally accepted that it is preferable to return any noise the screen picks up to source and ground it there, rather than sending it on to the receiving component and ground it there.
Once again a lot is going to depend on the input and output configuration of the relevant components.
Fully balanced.
These have signal and ground and shield connected to the plug at both ends; the shield is connected to the ground at both ends. This is the Pro audio favorite.
Its quite interesting to have a look inside the component enclosures and see how the ground is connected. Very few domestic Hi Fi components I’ve seen are fully balanced and even fewer are balanced and even fewer have a transformer (no physical connection from one side to the other) balancing stage.
One method of grounding shield I’ve used is to run the shield to ground using a long lead to my power condition box earth. In theory all noise picked up by the shield doesn’t enter the signal path in any of the components but you really need to do this with every shielded cable and equipment chassis earth. If its not done right you may get ground loop hum.
Single spur balanced Mains. Self built music server with 3 seperate linear PSU, Intel i5, 16 GB RAM no hard drive (various Linux OS). Benchmark Dac2 HGC, single ended XLR interconnects/Belkin cable. Exposure 21RC Pre, Super 18 Power (recap & modified). Modded World Audio HD83 HP amp. Hand built Monitors with external crossovers , Volt 250 bass & ABR, Scanspeak 13M8621 Mid & Scanspeak D2905/9300 Hi. HD595 & Beyer 880 (600 ohm) cans.
The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts.
-Bertrand Russel
John.