Infinity Servo Statics 1-A's....???

RWD, having heard all the speakers you've mentioned, I'd have to say that the closest match would be a set of ML CLS's with a hefty sub. If I recall, the high-frequency profile of the SS 1A was on the forward, sizzly side and I think the CLS's mimic that more closely than the Soundlabs.

I remember being totally blown away by the 1A system in the early 70s! That speaker had such immediacy and dynamic capability, and crispness it was just stunning. I'm sure the bass section could be improved upon, but those ESL panels were amazing! Alas, they had reliability issues and are long out of production.

If you're budget minded, a pair of vintage Acoustat 2+2's might be another consideration...

A used KLH Model Nine Electrostatics with a MUSE 18 or a velodyne Digital Drive 18.

I agree with Seadog1.The Servostatics used the RTR/Janzen tweeters,same as the KLH9s.I think they even use the same mid stat panels.The CLS is not as sweet and the Acoustats' highs will never be confused with the Janzen tweeter elements.Maybe Audiostatic speakers,but output will not be as high {SPLs}.