Pardon my intrusion, but as the North American distributor for German Physiks I hope I can add some information to the discussion:
by the way - to my knowledge, Huff has not had access to the German Physiks DDD driver for quite some time. Holger Mueller (owner of German Physiks) said that he had stopped supplying the driver to OEMs some time ago.
Also - with regard to the technology in the German Physiks DDD driver - it is not a "truncated" Walsh driver as one suggested, but rather a bending wave driver (the Walsh was a purely pistonic driver, which was at the core of its efficiency issues).
The DDD is actually made from microns-thin titanium foil or carbon fiber, and the voice coil is not fixed hard to the cone but rather acts as a striker might act on a bell, causing predictable distortions in the surface of the foil ... which in turn project the sound into the air.
It is true that the DDD does not perform into low frequencies the same way the original Ohm driver did. Then again, it also doesn't require megawatt amplifiers to come alive, not will it melt down the moment it starts getting enjoyable.