Don't underestimate the power of the bass. I didn't think the Symphony's organ had much bass at all, but coming out of a 15" HC-12 speaker, it managed to rattle the floor of the stage a couple of months ago, and for the Organ Symphonie, my students "felt" it in the back of the balcony. I've noticed that when I move my organs from place to place, for some reason the bass can be rather non-descript in a smaller setting, but in a larger venue, it takes on a life of its own--it's the upper frequencies that need reinforcement.
Hope this helps.
The other Michael.