Does Time alignment and Phase coherency make for a better loudspeaker?

I well-remember the magic of listening to Dunlavy's in Colorado Springs years ago in The Sound Shop, at a friend's home with IVs, and listening with John Dunlavy and meeting him (a wild guy) in his CS facility. They were very special but a tiny magic zone. For generally superb musical quality but one-person listening, they might get on my list.

As for knowing if I can really hear time and phase coherency, I'm not real sure of my ears unless someone told me what to listen for. I might be able to with a bit of learning.

I do know I am very sensitive to frequency adjustments and much prefer the sound of a room that is bass-corrected and very minimally DSP processed to yield a flat frquency curve with care to time and frequency. A 'repaired' room always sounds cleaner and better defined with no loss of bass intended to be there originally.

For Thiel (and Vandersteen) time and phase coherency is their marketing hook but in both cases their designers combined a range of good practices to make their speakers sound great.

He list I heard was: Dunlavy, Quad, Spika, Thiel, Vandersteen

And we pretty much have the majority of posters here talking about their T/P aligned speakers.

https://www.stereophile.com/content/measuring-loudspeakers-part-two-page-3

I learned this past year how much diffuser panels helped with imaging.  Diffusers on the back wall brought the imaging into much sharper focus.  The next step was putting my speakers on springs.  That not only improved the bass but also increased detail and focused the soundstage even more.  Controlling room reflections has a big impact on imaging.  The springs isolate the speakers from the floor and reduce speaker cabinet ringing.   I saw the difference with accelerometer FFT plots.  As minor as that seems it makes an audible difference.  And remember, the Thiel speakers have a mineral front baffle that is very rigid but still benefitted with isolation.  

@tomic601 , You are looking at it the wrong way tomic. It has nothing to do with musicians on stage. Each instrument is a singularity. Lets take a bass drum. When the pedal hits the drum there is an attack followed by the primary resonant frequency of the drum. Some drummers dampen this which I think is a shame. The attack is at higher frequency and can get caught in the crossover frequency of subwoofers. If the sound of that attack reaches you at different times from the subwoofer and main speakers you first smear the attack and if the delay is long enough you get an echo. Improperly timed subwoofers numb bass transients. Also remember that time shifts phase. Everyone knows what happens if you shift phase 180 degrees. If you don't, wire one of your speakers backwards and listen to what happens. The effect is much less obvious at higher frequencies but it is there. listen to what happens to the image. In order to shift phase 180 degrees at 100 hz you would have to move a main speaker 5 feet forward or backward. This can easily happen with some set ups. Using a swarm system is a way around his problem. 

Even Levon Helm's ( RIP ) brilliantly damped kick drum has harmonics and reflections that allow the human ear to locate it and ascertain the acoustic reverberant space it is located in. Time and phase information in the waveform that makes it to the ear ... or not..