Classic speakers to hunt down used

EV and Really true older Klipsch may be a rendundant suggestion. Klipsch used EV drivers on their oldest Heritage Series types and may have had them OEMed for the later ones. What surprises me is that the question mentions KLH, Advent, and AR all of which have a polite prentation then EV whichi s notoriously bright and then classic Infinity which used hard to Drive but forward sounding speakers some of which even had electrostatic drivers such as emits and emims which have great clarity. What "sound"style is your true objective.
I Second the IMF-Fried BTW. They made some great Transmission Lines. KEF was still more English sounding even though Bud Fried was working in their group. When Bud really had his say Fried (IMF) went in a different direction. But, you might want to check out some older KEF it seems like they might suit you.

A JBL L-100 Century speaker is a great vitage speaker if you can find them.

Altec's. Model 14's on up.

I am too inexperienced on hifi to know what my style is - yet. I teach classical music, so I like speakers that are little dark sounding - not too forward. I like old Jensen and Tannoy coauxial 15 incher (too expensive though).

So please recommend any good sounding classics I can get for a few hundred $ on ebay.

I am now listening to an old Jensen alnico magnets, with an old Marantz receiver - and it does it for me. I can't think of modern gears giving me this much joy for this little money - although I don't know too many modern ones to be honest.

I heard so far:

Parasound
Nad
Krell
Arcam

I liked them all.

I am not familiar with Chinese Hifi - but heard good things about them lately - like Cayin tube amps. If someone knows of them, please enlighten me.

Basically, I am interested in any good sounding gears that are good value - I have to put together systems for 1 to 2 thousand $ and offer them to my music students for their education.

They need to hear quality to improve their ear, and refine taste. It's hard to find systems for that little money to do all that - but most parents can't see themselves spending more for hifi (sadly).

Thanks again for all the suggestions - I will hunt them down - my students thanks you all.

I owned, listened to and sold many of those speakers in the early 70's. The AR-KLH-Advent followed a certain lineage of Henry Kloss and the Advents easily outplayed most of the comparable box speakers in the day. The big AR3a was probably a better speaker, certainly better built, as was the KLH 5, but the Advent had a less wooly sound, at least when driven with the mediocre solid state receivers that were usually coupled with them.
AR made a 'big' speaker, called an LST, which Levinson later used in multiple sets- don't know what mods he performed on them. Those would be pretty rare, i think, and probably insanely power hungry. Most of those 'acoustic suspension' speakers were very inefficient, and were mated with solid state equipment which offered higher power and 'lower' measurable distortion.
I am not as familiar with the small Infinities of that day- their claim to fame was the multi-piece Servo-Statik, and later tower speakers with monster woofer arrays.
EV- other than horn speakers, I don't remember much in the way of bookshelf speakers in that era, except for one that was equalized, and actually sounded pretty good at the time. The name escapes me right now.
Best bet, imo, is a refreshed pair of Quad electrostats (aka- 57's) with a low powered tube amp. I switched to this kind of set up in about 1973 and never looked back. (Except recently, when I bought my first large horn set up, go figure). Good luck.