Interconnect Directionality

How do you know the twisted pair are identical with respect to directionality? They could be opposite from each other. Ditto the strands of stranded cables. 😩

To test directionality of a given strand:

try to use a small full range single speaker.

your test set up should be simple and so that you can change the direction of the strand quickly, in seconds.

Ie, that you can swap the strand direction, without moving. speaker on a low stand, the terminals of the amplifier and speaker right in front of you. Listening at point blank range, for certain effects.

Full range, no crossover, is best as there is less gear involved, less terminations involved, less phase skewing of the acoustic signal, to get in the way of your attempt at discernment.

Hook up the ground strand from the amp and to the speaker. Don't worry about it's directionality, for the moment.

Take a single strand to be tested, and run it from the amplifier positive terminal, to the speaker positive terminal.
 
Listen for speed and extension of highs, 'plosives, attack, transient speed, etc.

Flip it, quickly. possibly just holding the wire to the terminals/posts, so it does not need to be unfastened to make the next quick flip.

The faster cleaner more open direction is the correct direction.  Mark the amplifier end with a marker, or what not, try not to use tape as that adds mass and damping.

Now, take that discerned strand that was found to be correct in orientation, and move it to being from the speaker to the amp on the negative pathway. Put the amplifier end that was marked, at the speaker negative terminal end. that is the orientation of the 'return' leg, for speaker wiring, IMO and IME. Interconnects can be different.

Then, take the prior untested ground run piece and perform that same test again, on the positive leg between the full range speaker and the amp.

This is harder to hear on stranded wire, especially the cheap stuff, as it is totally muddy and muddled from the get go. The effect is easiest to hear in solid core wire, single strand.

Geoff, current is the flow of electrons, no matter how little or how many. 

Wrong again, buddy boy. The electrons are only charge carriers. They are not (rpt not) the signal, the charge, I.e., current, itself. The charge itself is actually comprised of photons. That’s why the signal travels at near light-speed. The electrons move back and forth 🔛 at very slow speeds, as I already indicated, about one meter per hour. Thus, in fact, for AC circuits their net velocity is zero. 🤯