What used speaker would you buy with $20,000-$35,000 and why?

Here’s a pair of the Linkwitz LX521’s with the ASP and multichannel amp - ready to go. I almost bought them... but... already had the Orions and couldn’t justify the expenditure for another set of Linkwitz speakers. Not sure the guy has sold them yet - you might check with him.

They sound like Maggies... but... with better bass and dynamics.  Same soundstage and imaging, because they're open baffle, dipole speakers.  I have the Maggies also... and... I prefer the Orions for the reasons mentioned.  Very much the sound of the live music performance.

https://www.audiogon.com/listings/full-range-linkwitz-lx-521-2015-08-02-speakers-07930-chester-nj

They also sound a lot like the Grado PS-1000e headphones mentioned above - which is spectacular... but... with a more realistic soundstage.

I will sound like a "broken record" with this recommendation, but based
on what I have heard, and considering that you can place these speakers
easily in a medium sized (or larger) room unlike Maggies, the Eggleston
Andra-3's can be had for under $15K with the new carbon-fiber based
midranges.  I had the Andra-2's and they sounded Very Real on acoustic
material.  On well-recorded pop or rock music (such as Steely Dan) they also were spectacular.  They have superb bass below 20Hz also, without
any strain.  Their only competition is a significantly larger speaker system
that can move more air or something else that you prefer the looks of.

Here's what one Orion owner said about his Linkwitz Orions on the Madisound site:

"Orion 4 Madisound/Wood ArtistryThe most important thing I can say is that this is the best loudspeaker I have ever heard in my life for reproducing natural acoustical music, regardless of price. It's not bad for electronic music either. Pretty universally excellent on rock, jazz, trance, etc., but especially good for classical music. The most natural, nonelectronic sounding human voice reproducer I've yet heard. It is dynamic, crystal clear, coherent, has thunderous and tight lows, and most especially captures in a most captivating fashion the space of a live performace in a way I've never heard from a non planar speaker, although much more dynamic and with a greater sense of ease than a planar can do. I speak being quite familiar with a variety of ribbon/planar magnetic, electrostatic, and other cone (including ceramic) speaker designs. I freaking love this speaker!"

And the LX521s sound even better.

Magico Q3,Q5 and S3 mk2 or YG Acoustics Anat Ref 2 or Joseph Pearl mk3 because they sound wonderful.