I recently read a magazine article regarding the introduction of the DQ-10s many years ago. The author met Jon Dahlquist at one of the big shows. At the time, the QUAD ESLs were the rage and the author entered Jon Dahlquists display thinking the DQ-10s were electrostatic copies.

He descibed his first experience with the Dq-10 phase array concept and I remember mention of the Ampzilla components.
What further intrigued the author is Jon had a pair of true Electrostatics in the corner of his display. Mr. Dahlquist would not demonstrate them and indicated they they were not yet ready for public debut. The outcome of those prototypes is unknown and they never made it into production.