After 7+ years, in my most recent experiences with the CLS 2z's I have found...
that the answer to this question may very well lie with what main power amplifier you are using to drive the panels!
If you look at my System (yes, I need to update it again...), you will see that I have the CLS 2z's lifted onto Sound Anchor stands, 2 Depth subs, and the Sunfire Signature Series II Architect chassis amp.
The Bob Carver designed amplifiers have always been my reference because they simply don't care about the impedance load. They handle it cleanly and with great power
reserves. They are also the only amps I ever tried that didn't overheat or go into "protect" mode due to the impedance load.
Last year I had the opportunity to obtain a Pass Labs X350.5 amplifier and this was somewhat of a game-changer. Not only can it easily handle the low impedance load, but this amplifier actually enables the CLS to deliver REAL bass output!
This realization has been a complete surprise to me. The Pass clearly maintains ultra wide bandwidth and linearity even in the most troubling of circumstances and it definitely shines through on the CLS's.
As a result of this new-found superby clean electrostatic bass as well as extensive attempts to re-tune, I came to the conclusion that the the CLS' mate perfectly with a SINGLE Depth sub. The second one is not only unnecessary, but detracts from the overall integration of the system.
The system has been configured this way since December and everyone that has cycled through and heard it has agreed that the bass quality and integration is far better.
...go figure!
Cheers,
Ray