Thank you for the fast comment. Somehow I have never seen a reference to it anywhere (although I have asked online). I do remember seeing it mentioned in the AR History pages I have read. But I do not recall reading any first-hand remembrance of it from anyone.
The room had the 3a, 2ax, 4x, 5, and 6 models, along with the AR Amplifier, Tuner, and Xa Turntable. I believer the Receiver was there also (the Model R, as it was formally known).
Ironically, my first system ended up being the AR Receiver, the AR Xa Turntable (with a trusty Shure V15 type 2 cartridge), and a pair of Dynaco A25 speakers.
I had that system for many years and loved it.
(I also had those green Superex Pro-B V headphones.)