I measure group delay of my Kali in 8 cm distance. and i find a very bad high diffrence at 650 hz. this is bad for hear ITD. So my idea was use a EQ to change the phase in this range to avoid this large diffrence and hear what happen . The old LP6 sound now ok in width and stereo depth and all the strange sound is gone. thats no snake oil tune i can hear it very much. there are people that say EQ sound always bad. maybe they can hear better ITD as i. some people can hear 10 µsec diffrence in mid range between left and right speaker. I hear only more as 40 µsec diffrence. there are hear example for ITD too on this page
http://acousticslab.org/psychoacoustics/PMFiles/Module07a.htm an a bass/mid speaker that is only able to play 5 khz -3 db (200 µsec) should be pysical logical that it can not produce good phase for ITD. so better speaker developers use bass/mid that can at least reach 15 khz and use no steep filters. step filters also cause lots of phase shift.
I think a better way to use the EQ is look at the group delay too and use the EQ in such a way that it make the FR better and also make group delay better. brain can frequency diffrence correct better i think. can hear when play music reduce high freq 10 db and hear it some minutes. then switch to normal and now the music sound as music have too much high freq. I notice that small band eeq changes sound worse. but when look on group delay it can sound good. I am only able to create a correct group delay of my speakers when not more than 12 cm away with measure microphone. tbe sure it is correct i use 8 cm.
here are my measure and settings. i have also a group delay post of JBL 104. this sound even more better in stereo width and depth of field. but this also have changes in Bass alot. tweeters have much less group delay changes. i think speaker developer should be look on the group delay and speaker testers should also show group delay of all speakers they tests
in my settings can see i use a 23 hz BW 6 HP. this soundbetter, can see in phase shift display of the DSP that it reduce Phase shift, because i need bass boost.