I am a critic of the idea that absolute polarity is readily audible or particularly important. A friend of mine has been a leading proponent not only of the idea that absolute polarity is audible, but key to musical enjoyment, and that the recording industry has deliberately reverse-polarized 92% of all CD's to sucker us to buy more and more with less satisfaction.
I've long cited the unsurpassed Lipschutz double blind testing published in JAES in the 1980's. Lipshutz showed that polarity is not audible in complex music period, but that it is audible on test tones and certain solo instruments like trombone using headphones more easily or speakers in some cases (and Lipshutz used the speakers with unmatched phase coherence, near perfect square wave reproduction, the Quad ESL-63). However, Lipshutz said it normally costs little to keep polarity correct, so that should be done when possible. (My friend discounted this research immediately. "Electrostatics can't do bass, and if you can't do the bass, polarity is moot." Even though he mostly found the effects of polarity in the midrange and highs.)
The lack of audibility of absolute polarity seems to also be the prevailing view among audiophiles I have met (other than friends of my aforementioned friend) so much that few even bother to get the absolute polarity correct when connecting speakers. If the speakers are out-of-phase, they simply reverse one to match. (I always track down where the error is and correct it, to preserve absolute polarity. I also use an up-to-date acoustic testing app and manufacturer provided audio files to verify the polarity on systems when I've completed setup. Or sometimes my own constructed audio impulse signals and an oscilloscope.)
I have conducted 3 double blind tests on my polarity-theorist friend, and he has failed to reject null hypothesis p < 0.05 on every one. All three were of a designs (changed each time, often taking years to construct) he was certain he could pass, as in piece of cake (he was going to market a polarity test kit). None of this altered his POV of course (it would be plausible to continue to maintain that polarity is somewhat audible, but not so much that it's obvious and therefore a big deal). Nor does the fact that he has sometimes changed his strong convictions about which recordings are correct (less so with equipment). Most of his judgements are subjective, though he sometimes also uses (incorrectly, I have many times explained) a schlocky polarity check gizmo, or "simultaneously" starting CD players.
My friend has very often asked me to test polarity subjectively (I have done so only a few times) and criticized me for buying equipment, such as the Oppo BDP-205, and Emotiva XSP-1, which lack a absolute polarity reversal switch. For a long time he only purchased CD players which had absolute polarity reversal switches for single ended (which are extremely rare, like a few NEC models). He also criticized many of my purchases as having reverse polarity by default (I tested them and they didn't, then he said they were tricked out to pass polarity correct for test signals only). To date, the only device out of 100 I have objectively tested having reverse polarity was an iPod at the headphone jacks.
If such switches even exist on CD players they don't control the digital outputs, which is all I ever use.
It has infuriated me that neither the Emotiva XSP-1 nor the exceedingly flexible (but now discontinued) Behringer DEQ 2496 have ways to control absolute polarity either. I believe there is such control in the miniDSP OpenDRC, but only if you connect a computer device to the miniDSP...there is only one physical rotary selector switch on the OpenDRC, which is used to control "settings" (you could make two otherwise identical "settings" with only polarity being different--what a hassle--but I use the "settings" differently than that anyway).
But I have long, long, long, overlooked the fact that I CAN control absolute polarity using the Tact 2.0 RCS preamps I use. I just have to press the menu button, scroll to the polarity control, and then the polarity screen comes up. From there, I can set the polarity of each speaker independently. This makes instant A/B testing impossible, which is why I have long, long, long overlooked it. When I first got the Tact I was hoping to do the polarity experiments my friend was asking me to do right away, but finding that I could not do instant A/B tests, I lost interested, and disparaged the Tact as having "no absolute polarity control."
But yet it does have absolute polarity control, it's just not "instant." It takes about 5 seconds to do the operation.
By that point, 5 seconds on the music has moved on, and is not directly comparable to the preceding music. Plus your short term direct audio memory is lost, all you have left is whatever memes you encoded from the music previously. The comparison is far harder...and virtually certain to produce false positives if you believe you must be able to hear differences. This is even more true if you play something all the way through, or just a few dozen seconds, in each condition.
But this is the type of thing "serious" audiophiles often do anyway. Including gray hat near-objectivists like me.
So I finally got around to playing with the Tact polarity control on New Year's Eve 2021. And my first subjective result was that being out-of-absolute-polarity sounded a trifle smoother. I might add that I am very skeptical I could hear this effect double blind. It's probably an artifact of the fact that I can't switch instantly.
Other than the likely null effect I am glorifying, I theorize something very different from my friend. In fact, it was one of many reverse arguments I made to him. I suggested his all-cone speaker system had magnetic distortion that caused more distortion when transients were played one way vs the other.
Notably, my friend did all of his actual double blind tests using headphones, which he considered most sensitive to everything...the best window on the recording. But it may well be that the headphones didn't have the asymmetrical distortion that his speakers may have had which made him believe so firmly in the importance of absolute polarity in the first place. However, he no longer listens to speakers but only headphones and continues to maintain the uppermost importance of absolute polarity and that most recordings get it wrong.
I don't have an all-cone system...but I do have a cone subwoofer going up to 125 Hz (crossed with linear phase LR8 implemented with FIR DSP). So, the woofer is important, and it's magnetic, and years of leading transients which tend to do one way could (I imagine) cause a slight magnetization inducing increased distortion. I imagine the distortion would tend to be reduced, and eventually undone, using reverse polarization.
So, taking my position that reverse polarization will diminish distortion immediately, and in the long run de-magnetize the woofer system, I've decided to try running my system in reverse polarity for awhile.
If I'm wrong, well polarity didn't really matter anyway. And if that is wrong, and my friend is right, 92% of CD's will sound better anyway. He taking this very seriously for over a decade now, and he finds reverse polarity nearly always sounds better.
My theory, that dynamic speaker magnetization causing distortion is involved, is objectively testable. I am doubtful I will find it, though I'll add that to the list of experiments I want to do in 2022.
According to my theory I will continue to get lower distortion in reverse polarity until I have operated the subs for the same number of years in each absolute polarity. Then I should reverse them again.
Come to think of it, electrostatics could have a long term "memory" distortion effect too, in both the transformers and the diaphragms too.
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