Interconnects, some have directional indicators, why?

+danvignau The shield should be connected only at the source end so that any interference that is picked up by it is reverted to the source and not transferred to the input device. This lowers the susceptibility to interference from electromagnetic signals in the surrounding and therefore improves the signal integrity. One exception is microphones where the shield should be connected at both ends so that the casing of the mic is grounded. The same applies to turntables/tone arms and battery operated equipment if no separate ground connection is used.

The shield can thus be considered as an extension of the source units cabinet.

And now we have claims of photons travelling down pieces of copper.  I guess that would be responsible for creating a truly holographic imaging experience.  No wonder this topic always sparks controversy.

The audio signal goes in with positive wire and backs out with negative wire.

That is not correct. During one half-cycle of each of the frequencies that is present the current corresponding to that frequency flows in via the positive conductor and out via the negative conductor. During the next half cycle of each of the frequencies that is present the current corresponding to that frequency flows in via the negative conductor and out via the positive conductor. The directions of the current in each conductor continue to alternate during successive half-cycles. Meanwhile, energy is transferred in just one direction, from source to load (assuming the load is resistive), with the alternating flow of current through both conductors being essential to that process.

BTW, the "positive conductor" is often referred to as the "signal conductor," and the "negative conductor" is often referred to as the "return conductor" or "ground conductor," but the electrons and the energy that is being transferred don’t care about names.

Regards,
-- Al