By popular demand.

I know them well! I have been party to the destruction of three of them.
Mark Levinson made a stand that stacked two Quads on either side of a Decca ribbon tweeter. The system was finished off with two 30" Hartley subwoofers. It was driven by six 25 watt John Curl designed amplifiers.
In trying to get it tuned properly we destroyed I don't know how many ribbons and three quads. The system went deceptively loud and the Quads never sounded stressed, they just fried. Eventually, we got the hang of it and the slaughter stopped. As far as I know we only sold two of them. This is in Miami, FL. 
That Quad is a magic speaker. It has that ESL rightness that is lacking in dynamic speakers. Back then it was the only one readily available until Acoustat launched the Model X which was hopelessly colored due to a really bad cabinet. With the Monitor series they finally got things right.
If you come across another pair you might try stacking them. Just a thought.

Indeed! Impressive story. I've had the pleasure of hearing stacked Quads with a Decca Kelly ribbon on Croft OTLs. No subs. Large room. Opera. Late 80s. Nice. 

If you come across another pair you might try stacking them.

Not enough room and I prefer the superior focus and intimacy of the point source from the single pair.

Fair enough. Very difficult speaker to match subs to. The Harleys never quite made it. If you ran them up higher to take the load off the Quads they became very noticable. I do not think even digital bass management could have gotten them to work. 
I would love to try four 10" drivers in two enclosures, balanced force configuration with a digital crossover which I know is an enanthema to you but an analog one would never work. Nothing like a challenge. The single most noticeable defect the Quad has is the lack of low bass. The rest is so endearing that most Quad users are happy to overlook this and for the sake of purity, Quad users usually shun anything digital. Given the performance of early CD machines very understandable. Digital has moved on. As long as it stays at 24/96 and higher it can be very listenable but, it does sound different than vinyl. I agree with Michael Fremer on this one. As long as conversions are done at 24/192 or higher they are invisible.