Thank you Morst for explanation and schematic. Perhaps I understand what you mean. Dividing the signal into two drivers causes problems in the frequency range where the two drivers overlap. Comb filtering can occure in this frequency range in the room. And it is possible to hear it.
But EQ only works with one signal. There cannot occur comb filtering. I don't know if anyone can hear this little phase shift caused by the equalizer. I can't even think of a way to test it. Maybe by listening to standard eq and linear eq. But linear eq brings some artefacts into the signal. The comparison would be inaccurate.
Interesting points about comb filtering.
I'm not primarily looking at it from the perspective of comb filtering, I'm just trying to simplify the ideal signal path to result in less distortion, including phase distortion or as I said, group delay
I recently (the past 5 years) started learning the science of Meyer SIM and Rational Acoustics SMAART analysis systems, and one goal of system optimization seems to be flattening out phase artifacts at the perspective of the listener.
Intuitively to me, providing a signal to an optimized system which has been time smeared is not as ideal as providing one which has not.
I hope this is informative and not overly confusing. The stuff I'm learning on the subject is somewhat mind blowing, so I'm sure I don't understand it all, and I love discussing it because it helps me to understand more.
Here's a good intro video with Merlijn Van Veen of Meyer Sound, posted in may 2020.
https://youtu.be/cfhqHxod9D0