Highstream, I have some Audioquest XLR splitters (conventional, as sold on their website, not "reverse" splitters). I had to go to a guitar/music center to find the appropriate reverse 2 to 1 XLR splitters. They can also be found on Amazon, but are lower quality.
The outer versus inner designation simply refers to the orientation of the two cables used with the splitters on RCA or XLR only, not with Y cables. I do not concern myself with any kind of "twist" when using the Y cables, only with hard splitter devices. With a hard splitter cables can either be kept parallel, or a half "twist" put in them by moving the outer cable to the inner position and vice versa on one end only.
If you have any qualms about testing, please consult your equipment manufacturers first. This is a do at your own risk activity.
I have not encountered a possibility of using the Schroeder Method to subwoofers, so I cannot advise in regards to that.
If DAC to active speakers would prove to be efficacious, my guess is the result would be brilliant. I would not try it unless conferring with the manufacturer.