random info...
often it's said that ILD & ITD dictate that phase doesn't matter for high frequencies. It's a notion people have inferred from light reading... and it's not entirely correct. The truth is, time alignment absolutely affects high frequency response. Now, the result isn't as dramatic as it is with midrange frequencies where you can hear the center move left and right with little adjustment between left/right t/a values. However, the time alignment allows a cohesiveness that you can't get simply by adjusting polarity of tweeters. I've often noticed in my car that cycling through T/A 3 times (roughly equivalent to 0.06ms, in 0.02ms steps) results in a full 'phase cycle'. Listen for the "s" sound ... aka: sibilance. Cycle through your T/A and listen for that sound to move out of phase and then *pop* back in phase. You may find the center moves a bit to the right or left, depending on what channel you're adjusting. But this is pretty minor unless you have your tweeters crossed really low. What you'll likely find is that you get in a cycle like I've mentioned where you can literally hear the tweeters pop in phase. Try it. Seriously. You'll notice it. Just shut everything off and leave your tweeters on.
To illustrate what I've said, here's a comparison of the tweeters in proper polarity; adjusting the left tweeter so it arrives at the same time the right does. The red is with no time alignment. The orange is with time alignment done by ear. See how the red is about 2dB lower than the orange? The orange is in phase and time delayed to match the wavefront of the right side tweeter.