Crossover settings isn't a wall, but it's a more of gradual fall-off. Looking at 685 measurements, I'd definitely not crossover it with the sub at 50hz, but much higher at 90 or 100hz
www.soundstagenetwork.com
Room 15x22 ? I assume it's in feet? What's the height? Is it open to other spaces/rooms? If so - what's the total room volume in cubic feet?
Assuming room is sealed (by walls/door) and you have 9ft ceiling height - that results in 3k cu-ft volume and according to our own Room size ratings, that falls at Large Room.
This article outlines our test procedure in determining a subwoofers room size recommendation based on its max CEA SPL output while making room size and subwoofer distance assumptions.
www.audioholics.com
Tom Andry (one of AH founders and a contributing author tested SB and PB2000 subs (older models) and SB2000 was recommended up to medium rooms, where more output pb2000 is ok for large rooms.
If you don't mind waiting VTF-3 MK5 HP sub is what I'd go with.