Don't get me wrong here. I indeed respect what you are saying. But you are factually incorrect. Yours are not refutation facts. They are your opinions; which I do respect. But I also respectfully disagree. 20 years worth of experience on a thing doesn't make one correct. It just makes one knowledgeable. I personally am a master degree engineer from one of the top universities in America. But that doesn't make me right about anything and everything engineering, except for what I study, examine, experiment with and prove workable as fact. Look it; if you've done this for 20 years, you should know better than anyone that audio, even more than video, lends itself to constant experimentation. This entire AVS Forum is a testament to that spirit of experimenting. This project wasn't even ambitious as you stated. It was easy and accessible because I already had the necessary equipment and HK provided the capability in the AVR745. Don't shoot at me if you disagree. Shoot at HK and their scientists/engineers for including this capability in their product. Obviously they agree with my POV, that this is worthy science to explore. I betcha they, Dolby Labs and others are not limiting their thresholds to 5.1 as you stated. If they can create validity for 40 speaker system arrays, they will do it because they will sell more products. Its up to us, the buyers to use this stuff creatively in our homes to create the best experiences we can achieve. I rarely feel limited by audio equipment. I experiment, within the limitations of that EQ to get the most out of it. I don't buy an automobile capable of going 180 MPH and dawdle along at 35 MPH in it.
Your point here is a good one and I agree;
"If your theater is long? Do multiple side surrounds and multiples across the rear. Just like they do in large venue theaters. It's still usually only 5.1 being fed to that and 6.1 / 7.1 being created.". Exactly!
That is precisely the point I'm making here. Doesn't matter if you use 5-7-10-12-14 speakers. The signal in is still 5.1 or 7.1/2. But as you should know, the sound arriving at the ear is quite different because of room and environmental effects. That's precisely the point of adding delays (either electronically, or via better speaker placement, or adding more speakers). That is what creates unique "discrete" sonic signatures in ones viewing/listening rooms. And this is not limited to 5.1 as you stated. The room itself enforces signature interaction and can render any sound as amplified, attenuated, discrete or moot. That's why they build Cathedrals huge and studios small. To control sound wave propagation. Dynaco, years ago (1970's) had a little, inexpensive, bronze box kit that one could make or buy assembled. That unique product actually proved and achieved the science that I am referencing here, spectacularly. And they did it without the use of DSP, 5.1, 7.1 etc. They simply inverted stereo signals in a small box and sent them out in analog/discrete/matrixed/acoustic format to achieve 4 channels of pure acoustic bliss. The signal out from the Dynaco unit was still stereo (2 channels plus 2 inverted channels). But based on point source speaker placements, one could manipulate their room environment, and daisy chain those devices in the signal path to create 4-8-12-16 channels of new unique sonic signatures that truly transcended "discrete" stereo.
Enough with the history lessons and proving points. Companies like HK make these wonderful toys for us to play with and experiment with. Many of their new ideas come from how we end-users actually use this stuff in our homes. You stated "I'd never set that up". Quite a bold statement. Not the type of curiosity that will ever get you to the moon or Mars. But it will keep you happy at home. I respect that POV. Well; since HK gave me the capability to try it in the AVR745, I did. It works perfectly; it was easy/not hard; it was natural/not ambitious; it introduced no problems/just unprecedented great sound; and you don't have to be an engineer or 20 year installment veteran to try it. Anyone can do it by just using more of the features in the product they bought.