You are quite correct about the amp phase situation and that it is continually in flux when a dynamic signal is being amplified if that sounds like a good way to put it Schmidlin.
I was referring to the speaker motor only as being intended by convention to move out ward first whenh a signal is applied as I understand it which would be where the industry standard comes in. Of course every once in a while there is one that somehow is reversed that shows up and needs to be hooked up " backwards " when more than one speaker is being used or they 'fight ' each other in the circuit.
Technically or electrically they could all be hooked up backwards and it would probably not make much difference to the sound coming out of the amp. This has been discussed here and elsewhere i.e. does it matter if the speaker/speakers are pushing or retracting first when a signal is applied and as I understand it the jury is still not in agreement on that one.
Interestingly depending on the number of gain stages it seems that two amps can be 'out of phase ' with each other while still being internally ' in phase ' in the circuit which can create problems with multiple amps being used of a number of sorts , but that's a different discussion .
If I misrepresented push and pull as plus and negatrive for simplicity I appologise . My intention was to equate outward movement as push or plus movement and compare it with inward movement as retraction or negative movement which would be the same electrically if the speaker motor is hooked up in the conventional manner as I understand it. This is almost impossible to see with a dynamic signal but shows up with the 9 volt trick making it simple to decide which connector is positive and which negative .
Outside of that the conventional wisdom seems to be that it is almost if not impossible to hear any difference whether the speaker is hooked up in either direction with only one in the circuit.
Now just as a point of contention if the speaker is hooked up differently than say the speakers in an extension cab will it effect what is heard or electrically cause changes in the way the signals move through an amplifier ?
If no then no problem but if yes then having all speakers hooked up the same way seems like a good idea to avoid future problems.