I use a single S3000i in my 3,400 cu. ft. room (that’s rather open). It shakes the walls, my feet, my couch and my body. And it’s sitting 9-1/2 feet away on laminate flooring over a concrete slab. It’s a powerful subwoofer. Your room volume is less than half that size and isn’t open, so I would fully expect the S1500 to be as impressive in that smaller volume. I would always tell a person to try out a single sub first. If there are problems with room modes at the MLP that moving the subwoofer cannot correct, then you can always order a second.
Music area: Magnepan 3.6, McIntosh MC2205 amp & C48 preamp, SVS SB13-Ultra, Oppo BDP 95, dbx 3BX, and assorted equipment.
Movie area: EMP Tek E5Bi (were rebadged to R5Bi), RBH/EMP Tek R55Ti, PSA S3000i, Denon X2000, Oppo BDP 83.