Excellent post, FrantzM. And this is exactly where I'm at currently- a baseline with incremental improvement likely in the next few months.
There are certain things like phase shift that are difficult to measure by "ear" and in normal listening environments can make larger differences than frequency response allegedly. I'd be curious to how some of the pros on this thread account for it.
Phase shift in the context of speaker positioning is not that hard to do by ear provided you use a mono music signal and not stereo. Just start stacking instruments bottom up. Using pink noise, you'll know you've got it when you get a spherical bubble of noise in between the speakers. Phase coherent speakers definitely help but the method will work on any speaker. You'll end up with very sharp imaging upon return to stereo tracks. Not everybody likes razor sharp imaging but I find it a better place to start than from the opposite direction. You can always soften the image to taste afterwards.
