Hi,
Yep, enormous amplifiers, although the purpose of sticking the driver in the wall of one room is to prevent the bass energy from sneaking around and canceling out the bass waves from the back of the driver. That's why a driver with no enclosure isn't loud, because all the bass cancels out.
Remember, bass is omnidirectional.
I haven't heard an infinite baffle speaker in years, but they go way, way back to the early audiophile days in the '50s. Edgar Villchur, the founder of AR, and the inventor of the "acoustic suspension" compact sealed bookshelf enclosure used the infinite baffle as a starting point. He developed a woofer with a very loose suspension such that it would operate almost as though it were in an infinite baffle installation. The first AR bookshelf speakers would produce bass to below 30 Hz, but they were very insensitive and required large amplifiers. Nevertheless, they produced much smoother and deeper bass than big, folded-horn enclosures of that era, and were, by comparison, quite compact.
Regards,