Riddle me this....

Exactly.  Jobim said it best in the English lyrics to Desafinado.

Have vocalists and instrumentalists also learned to record in phase with each other.? My point is if one prefers one phase vs it’s opposite it’s possibly because one is focusing on one aspect of the performance, eg, the vocalist in an ensemble.

The answer to my rhetorical question is there is no difference between switching phase 180 degrees in balanced analog mode vs digitally. Except in the latter case the signal has to be reconverted to analog after phase is altered.

Explain to me why the phase switch ought to be in the digital domain, as opposed to the analog domain in a fully balanced analog circuit, where ground floats. That's assuming of course that one only wants to be able to change phase by 180 degrees.  If one wants to change phase by other parameters, e.g., 90 degrees, 270 degrees or etc, then of course that is best done digitally.  But here we are talking about the effect of changing phase by 180 degrees. 

My ESLs are full range with no crossover. Is that phase coherent?

antigrunge, I hope you and anyone else will get the point that I don’t claim phase makes no difference. Please pay attention to the double negative in that last sentence. I do claim that (1) I, and everyone else who has been subjected to double blind testing for phase sensitivity in my listening room with my dipolar full-range ESLs, cannot hear any difference, and (2) I am not convinced by any argument I have read anywhere, no matter how erudite are the discussants, that changing the phase of an audio system by 180 degrees necessarily ought to make a difference to the listener. Get that last point too.... I don’t see why it ought to make a difference, because there are many counter-arguments that seem also valid and which would lead to the conclusion that phase reversal (of both channels) would just as likely make no audible difference. Seems to me as soon as you have two or more sound sources on one recording (e.g., single piano plus single human voice), the importance of phase in the listening room begins to break down, because the phase relationships of the sounds emanating from those two or more sources is not going to perfect, even if they were recorded using one microphone. Of course, if you are listening for the voice, and if you have "correct" phase for the voice, then that might sound "better" than optimizing for the piano. Dunno.

For the many who say they do hear a difference, how do you know that the difference you hear has anything to do with changing phase? You might have a dirty phase switch or when you switched speaker wires, maybe your new connection is better or worse than the original because you tightened down the connector with such conviction. There’s also expectation bias, etc.

Jea48 tells some other guy to listen for himself and then provides three URLs that take you to arguments FOR the importance of absolute phase. Better to listen for yourself first.

The question is what is "absolute phase" in reproduced music where the music itself has been recorded using several different microphones, set up usually without regard to their relative phases, and is then played back through speakers with crossovers and drivers which are a further source of phase error even including sometimes 180 degree differences in phase, and then into a room with reflections that further alter phase relationships. It is one thing to say absolute phase makes a difference but quite another to apply that principle to the reproduction of music in a typical home environment using typical source material and multi-way loudspeakers. And anyway even after all that, the question is only whether a particular individual can hear a difference. It is not necessary for me to deny there is a difference in order for me to report I cannot hear a difference. I attribute my failure in that regard in part to the fact that I use full-range, crossover-less dipolar speakers. (In a dipolar speaker there is rearward radiation of the same magnitude as the forward radition that is 180 degrees out of phase.) And to test my own acuity, I have asked others to sit in my room while I switched phase by 180 degrees under conditions where the tested persons were blinded. No one I have asked to perform this test can hear a difference in my room through my system. And finally, I think we all can agree that the actual question posed by the OP, whether a point source is perceived to relocate precisely in space with respect to a 180 degree alteration of phase. The answer is for a particular listener it is possible a difference in soundstage is perceived but not a difference that can be described so precisely as described in the OP.  At least that is my answer.

Don’t keep us in suspense. What is the Wood Effect, and what does it say on this subject?

I just spent 5 minutes reading about the Wood Effect. This was on another audiophile website in an exchange that took place in 2008. Seemed like the guy who brought it up did not really understand it himself, something about changing phase by 180 degrees at the amplifier/speaker interface, both channels of course. Why would that be any different at all from reversing phase anywhere else in the chain? Then there was a discussion that basically devolved into one of those where believers in the Wood Effect inferred that those who could not hear it are somehow Philistines using inferior speakers. One guy claimed it makes a big difference with Sheffield D to D LPs because they are "phase coherent".  Spare me.

roxy, In your first post, I think you are thinking of the situation where one channel is 180 degrees out of phase with the other channel, in a stereo system. Yes, that causes very obvious problems, and needs to be corrected so that the two speakers are "in phase" with each other. The OP is asking about the situation where you reverse phase on both channels at the same time. Many listeners think there is a "correct" choice and say they can hear important differences when the choice is incorrect. For many boring reasons related to how recordings are made and room acoustics and the nature of crossover networks, I do NOT think there is a correct choice, so long as the two speakers are in phase with each other, but I do think that with many monopolar speakers and depending upon the room, there may seem to be a correct choice to some listeners (not to me in my room with dipolar speakers and using a panel of listeners who were blinded as to speaker phase). To each his own, in other words, in my opinion.

The logical extension of my findings for my system is I don't care a fig whether the preamplifier or any other component in the chain reverses phase (in both channels of course).  And I would not agree to the OPs proposition that inverting phase in both channels causes the image of the performer to move fore or aft.

Results Depend upon the type of speaker (unidirectional vs dipole vs bipole and line source vs point source), the room, and listener bias. But no, it’s not as simple as your proposal suggests. With my dipolar ESLs, I hear no effect at all of changing phase by 180 degrees.