I was thinking about this topic and it seems I agree that these speakers should have external amplification otherwise I'd have a problem getting power to them.
The adventure of thebland's system setup gave some good insights and helped give me some ideas that I am working into the shallow designs to better allow for the expected/desired placements for Atmos and related systems. I also have a few ideas which I don't think have occurred to those designing the hardware or speakers quite yet, but I hope to talk to those more directly involved in a few weeks at CEDIA. The updated Spark can be powered externally in a case that will likely be similar to the outboard SubMersive HP+/F2+ amplification option I had announced here: The 2 way Sparks make wiring easy with commonly available wire such as this Belden wire I prefer to use or even this example for a few $ less.
Seaton Sound, Inc. firstname.lastname@example.org 773-290-8436