Directionality Explained

Just to add something a bit more specific.

Here is: the current is symmetric, no argue there. But the voltage is not.

For example, as the current flows from the amp to the speaker, due to loses from heat, the energy will be less and less as the current flows toward the load, in this case it's the speakers.  That is the amp will send some energy out, but by the time the energy arrives at the load will be slightly less due to loses such as heat.  If the energy is the same, it would violate the conservation of energy law.

Energy is equal to = V * I.  And since I is symmetric, then it's must be the voltage that is NOT.  That is voltage at the amp end will always be slightly larger than the voltage at the load (speakers).  

If you are using current for your argument why wire cannot be be directional then you will need to prove the electric charge carries the signal from the source to the load. And you know you can'

That isn't what I said. I'm not talking about energy flow but charge flow and if a wire is directional (affects the charge flow different depending on which end voltage is applied to) then it's  measurable. Whether that affects anything audible I never said. 

This has to be the baseline to start from. Not just for cable directionality, but why cables sound different. Why the type of dielectric used to cover the wire makes a cable sound different.

I put a 1000 gram weight in your left hand. I put a 1000.1 gram weight in your right hand. Absolutely those weights are different. There is no way one could dispute this and claim they are the same. However, if I was to ask you which one was heavier, you wouldn't have a clue and if 1000 people did the same test, the results would be 500/500 approximately or purely random. No knowledgeable engineer or physicist would dispute inherent directional effects in a cable or any other multi-element series/parallel circuit for that matter. Similar to the 1000 and the 1000.1 grams weights, there is a big difference between a "technical" effect and one that is detectable by a human being.

This "directionality" at least as it applies to audio, would be easy to measure and/or quantify .... sort of like dielectrics, and once quantified, could be evaluated if within the realm of audibility. Transmission line effects are well understood and would be orders of magnitude below audibility. Most bulk circuit effects, i.e. resistance, inductance, capacitance are not even at the level to be audible (unless poorly designed/specified). The direction differences in those values, unless intentional, will be orders of magnitude below that .. or inaudible.

This "directionality" at least as it applies to audio, would be easy to measure and/or quantify .... sort of like dielectrics, and once quantified, could be evaluated if within the realm of audibility

Using this logic, then all cables should sound similar since human hearing can hear any difference. 

Most bulk circuit effects, i.e. resistance, inductance, capacitance are not even at the level to be audible (unless poorly designed/specified).

Again, this logic suggests that our audible ability is so poor we couldn't tell the difference.  But it's been shown our hearing is highly acute.

The direction differences in those values, unless intentional, will be orders of magnitude below that .. or inaudible.

Certain an opinion and not a factual statement.  

There is also the voltage law which must follow the conservation of energy

The voltage changes around any closed loop must sum to zero. No matter what path you take through an electric circuit, if you return to your starting point you must measure the same voltage, constraining the net change around the loop to be zero.

Read this it will tell you everything you want to know about electrical circuits and then some. There is also some good links into sound and hearing read those too.
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html