I, too, was amazed at what I heard in that room. The purity of the Sanders ESL's but without positional constraint. Effortless is a very appropriate description. I am a planar lover, and these are the only speakers I have ever heard that bettered the original Apogee, to my ears.
Anyone heard the Alsyvox Botticelli planar speakers?
Full range ribbon tweeter/midrange and push-pull planar magnetic bass driver. 22Hz to 40kHz. 94 dB efficient due to all neo magnets. 260 lbs per speaker. Has garnered enthusiastic show reviews. BTW, "only $87k". Looks beautiful.
https://alsyvox.com/
https://alsyvox.com/