I got around to connecting my newly acquired Essence Audio 10A Reference speakers today. Here is a pic of the assembled speakers being driven by my almighty ZMA. These are lesser efficient speakers and definitely welcome the additional power the ZMA offers.

Based on the owner's manual that Ron retained (could be the only one in existence!), I was able to determine some basic specifications on the speakers. They are 8 Ohm, 89dB efficient with a frequency response of 18Hz - 35 KHz!
They are very interesting and unique speakers. Apparently, there were only about 100 pairs ever made by Dale Pitcher. They are comprised of five transmission line modules, stacked from largest to smallest. On the bottom is the bass module, followed by the mid-bass, midrange, tweeter, and super tweeter modules.
The key to these speaker systems is the alignment. Dale included five alignment charts (one for each module) that is to be used to properly setup and orientate each module in relation to one another. The purpose of this exercise to to make sure that based on the distance from your ear to the ground ("B") and your ear to the top center of each module ("A") each module is in proper alignment to the module below. So, you start with the bass module. You then align the mid-bass to the bass, then the midrange to the mid-bass, and so on and so forth. The reasoning behind doing so is to ensure that the timing is perfect, or as close as humanly possible. Dale was big on making sure that the sound produced from each module arrives at your ear at the same time. Aligning the modules is critical for this to occur.
Here is the "Bass to Mid-Bass" alignment chart....

Anyway, I wasn't sure the ZMA would have enough juice for these big boys but they are driving them quite nicely! I have not taken the time to precisely measure and align according to the charts, but my plan is to do so tomorrow. Fun stuff!