Stacking 2 subs will mostly just give greater output with reduced strain to the original single subwoofer. Dual stacked subs can possibly also smooth out some bumps in the curve, but don't count on it as it's totally dependent upon EVERYTHING to do with the room and placement.. . . . but seriously thinking of stacking 2 more 1100X (one each on top of the existing) BUT not sure if it would add any value? Thoughts?
It's when using 3 stacked subs that more tuning is possible. Going higher means including the ceiling reflections as well as the floor. Lots of fun stuff to consider. I've tried these things and came away with just lining up a bunch of subs along the front wall as close to the floor and front wall as possible. This horizontal array is much easier to deal with as opposed to two tall stacks that are not smashed into corners. Horizontal allows for better seat to seat response without much effort, and removes some of the floor bounce to be expected with drivers being greater distance above the floor vs right at floor level.
The subwoofer type I really would like to have is In-Wall mounted. I'd love to take as much SBIR away as possible.
I haven't had any extra time to play for months, but am gearing up to having a fun Fall. So I had a setup that was very good until I moved everything to swap tv panels, and just haven't put it all back.