After a week of setting up, my review of the system is consistent with the one I've posted.
I ended up moving the speakers forward 3 feet away from the wall (I have other things in my room so I can't move them that far away). The imaging improve marginally, a bit cleaner.
Did the crawl test, and the subs are about the same relative place, with two against the front wall and two behind the seating position.
The phasing was next, using the reverse polarity method, and since the subs are all about equal distance from the seating position and in the relative to the speaker. So all phasing ended at pretty much zero.
Crossover same concept, I paid attention to low mid range harshness, and tuned it to a point where harshness is gone. Starting with the pairs closest to the speaker, the ones far away should not be set higher than front. If you still sense harshness, the ones closer to you should be crossed over lower than the fronts.
Volume is fun to play with, if you set them all the same you get a better sense of space, but if you set the front higher than the rear, you get stage imaging. I'll play with this setting and see what comes from it.
The sound is effortless and cohesive extending the dynamic range of my speakers and enhancing the sense of space. For about 2 grands its a deal compared to not even the price of one high end sub.
