With that large of room, Audio Kinesis Swarm is worth checking out. Mcarbon used the same Audio Kinesis Dayton amp and built his own swarm from 4 unassembled box speakers from Dayton. I used car audio sealed sub boxes and Kicker drivers. Now trying find space for a 4th sub box, my room is much smaller than yours. As gochurchgo mentioned 6 are even better for a large space. I have a very good friend that sells car audio, hence my choice, and he insisted on letting me pay cost only. 2 years ago we built a Howe truss bridge across a creek on property he owns ten miles out of town in the woods.
Subwoofer insight.
This is new territory to me. Current speakers are 2 way with frequency response of 60Hz-20KHz with +/- 2dB. Sensitivity rated as 86dB. Chance to purchase a pair of REL 7 tis. I feel like I am missing something but will have to buy the subs to try out. My basic question is this. Does this purchase sound wise? I know what I am willing to spend but do you think I will notice an appreciable improvement. I know that no one can listen through my ears but this is my first time doing this. Source is 75 watt integrated tube amp, McIntosh MA-2275. Thoughts appreciated. I am leaning towards going forward with the deal but would appreciate some feedback. Room is large and open, 28X38 feet with 9 foot ceilings. Thanks for any feedback.