Phase Inversion, to flip polarity or not

I use to use a preamp that allowed for polarity inversion by remote control so that one can easily A-B the difference.  In my system, the effects of flipping polarity varied greatly, depending on the particular recording.  In most cases, the change is subtle and whether one or the other polarity was better was not clear cut.  For example, even in one particular cut, one polarity may make the vocalist sound more "present" but the piano might sound slightly "phasey."  It might well be the case that polarity is not consistent between different parts of the same recording.  My preferred polarity, when I bothered to listen for this, varied from recording to recording, so it would make no sense trying to set up a system to consider polarity; if that is important to you, a switch of some sort would be needed.  

You can buy test CDs that have music presented in two different polarities so you can hear for yourself it matters.  One example is the Jazz sampler/test CD from Chesky Records.

One of the reasons I stuck with planar speakers, for so long(Acoustat Model III’s, were my first, in 1981/Magnepan, until 2017), was the knowledge that they were inherently time/phase aligned. The obvious/audible benefits of which were learned, through mirror imaging a few customers’ DQ-10s, back in the day. I’d always actively bi-amped the planars, with my own bass units, physically aligning the acoustic centers of the drivers and panels and enjoyed excellent reproduction. Things certainly became easier, when TacT/Lyngdorf came out with their DSP/active crossover systems, relaxing the need for exact placement. Again- SO MUCH depends on the attention paid, by the people laying down the tracks. It’s nice to know(once one tests and confirms that their system is doing it’s job correctly), if something’s askew; it’s the recording.

Not to mention the drivers in your speakers may not all be in the same polarity- phase. Some speaker designs change polarity for different drivers. 

 Interesting analysis kost_amojon, I  will have to think about this.  For my part when I have had a phase switch I seemed to notice changes on transients such as cymbals.  Otherwise I haven't ever noticed much.  I take notice about the observations that recordings may or may not be in or out of phase anyway.