My affair with audio began in 1968. The early ear opening experiences with amazing speakers were with Rectilinear 3s, IMF TLS-80s, and Quad ESLs. Of the pre-1970 Boston area bunch, KLH 6s were best to my ears, but I never heard 9s. It is true a lot improved as the 70s progressed.
All Pre 1970 Vintage speakers suck! Prove me wrong
Have tried many vintage speakers.
My conclusion: All pre-1970 vintage speakers suck. Well-made but crappy sound.
Used with both vintage amps and modern.
I do like many vintage amps such as Radio Craftsmen RC-500, Marantz tube, Scott tube, Heath W5, Lafayette and Pilot tube.
But back to pre-1970 speakers:
No bass, harsh, or honky mids and no highs. Not musical or listenable to me.
Tried many including Acoustic Research AR-3a, 2Ax, etc. The entire AR product line. Also Klipsch Horn, Large EVs. Altec VOTT. Pioneer CS-88 and 99.
Nothing pre 1970 is even close to the better modern speakers.
I challenge you: Prove me wrong.