Has anyone tried double CLS

Greg, allow them their fun. It will be a time consuming and expensive learning experience. And I'm charmed by their enthusiasm:

Since the CLS panels are mirror imaged you would not want to stack them but put them side by side. One right channel with one left channel edge to edge (side to side).

Good grief!
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I must repeat, the double CLS are not stacked so you do not need ceilings any higher than you need for a single pair. The speakers are wired in series exactly as the gentleman has described and the load to your amp is not as severe as with one pair.You only need to find a used pair of CLS and 1 extra speaker wire per channel( I use 6 separate 3 foot wires)This is a very inexpensive,upgrade that anyone can perform. There is no external crossovers, no extra sub woofers and interconnects, no pain in the ass positioning of a sub to where it sounds best( like I have done trying to get The Depth to disappear)no soldering wire, replacing or upgrading internal parts or connectors,no power supply upgrades,no power cord upgrades.None of the things audiophiles spend small fortunes on trying to improve their sound.If you find a used pair in the $1000.00 range that is the least amount of money for the most improvement you will ever make to a single CLS system.No expensive time consuming learning experience here.The fun and the proof is in the pudding. And in putting together a double pair.I would feel grief to those who spend five times as much money and effort futzing around with power cables and speaker wire upgrades in a vain attempt to better the sound of their single pair.Good grief, don't knock what you don't know and have no hands on experience with.Do you still think that if man was meant to fly he would have been born with wings?

Sorry Lacee, I would never do that. The CLS (Curvilinear Line Source) is designed to provide a single, uniform, wavefront. Good dispersion, not generally a feature of flat electrostatic panels, is achieved using the (single line) curved driver. (Soundlab achieves a similar result using many smaller flat drivers in a curved array.)

Placing two (curved) lines side by side will create addition and subtraction nodes resulting from combining the two offset wavefronts, and will produce reinforcement and/or subtraction nodes all the way out in to the listening space. This cannot possibly reproduce an accurate soundstage hologram, rather just a "wall of sound".

Nor will adding more panels change (extend) the bass response lower than that of a single panel as Greg points out. If you are not getting adequate performance because the amp is having trouble driving an admittedly difficult load, then get a different amp, or perhaps try using an autoformer like the one made by Paul Speltz.

This subject has been covered ad nauseum for years. If you want confirmation of the points I've made, I suggest you speak with Jim Power or one of the other senior technical people at Martin Logan. It's a dead issue for me ;--)

As for stacking the old Quad 57s, that's an entirely different matter. The (individual) electrostatic drivers (1 bass in the middle 3 HF each side) run vertically top to bottom. So stacking 2 of the them still results in a uniform wavefront, twice as strong. A good thing too because 57s didn't play very loud without arcing and burning up! Again, this arrangement didn't increase their upper or lower frequency response specifications, and when Mark Levinson designed his "Super Quad" system, it consisted of subwoofer and super-tweeter units as well.
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The more panels, the more radiating area the more sound.Is this too hard to comprehend?The stacked Quads didn't magically have any different bass than they had before.They did not go lower.The bass just radiated into the room more so that you did not feel the need to augment it in any way.This is what I have found by doubling up on the CLS.My claim is that there is more bass, not deeper or different sounding bass.Just more bass power ,if that is easier to understand.The bass no longer feels like the poor country cousin.There is more bass loading the room.Would you have us believe that an Acoustat 2(2 panels per side) has the same bass energy as an Acoustat 4( 4 panels per side)?Yet this is your argument that an extra set of CLS will make no difference. The basic principal involved is air movement.More panels more air movement.More sound in the room is generated by 4 CLS as there is by 2.This is like saying that the panel sound from a pair of Aerius is no different than the sound generated from the Summit panels. It just isn't so in the real world, or in my listening. Larger panels, more sound.Four panels equates to more sound,and there are no problems.Addition and subtraction nodes?You should get some hands on experience and not postulate wild assumptions.What about the nodes created trying to pair up woofers and stat panels?Why do you think that most stacked or doubled up Quads systems don't have subs? I am sure there were a lot of people who said it was blasphemy and that it just wouldn't work as well.In any event,this set up works for me and it will for those who try it.

I think you don't know much about the Quad ESL.There is one treble panel in the centre of each ESL 57,flanked by a bass panel to either side. Three panels per speaker only.
So when you stack you get 2 treble panels and four bass panels per stack.You get more of the bass into the room this way and the result is you do not feel the need to add on subwoofers,neither do you need a super tweeter.When you add the subs and super tweeters you change the sound of the Quads and move into territory that is frought with problems,beaming tweeters, booming bass.Talk about room node problems. Doubling up on Quads or doubling up on CLS is not meant to change anything about the sound of either speaker, and I have never claimed it would.It is all about delivering more of the sound you liked about the speaker in the first place.