I run a vintage system downstairs (separate from the main system shown in my profile here) that consists of a pair of Quads I bought in 1974. They were restored by Kent McCollum at Electrostatic Solutions in 2017. I had put them away back in 1990 in favor of a pair of Crosby modified Quad 63s. In both cases, I originally drove them with a succession of ARC tube amps in the 60-70 watt/channel range. They were both revealing speakers, though I preferred the original Quad to the 63.
When I had the old Quads restored, I also had Bill Thalmann restore a pair of old Quad II amps which make about 15 watts each. I have extremely good glass in these- real GEC KT 66s that I found some years ago, NIB, along with the proper Mullard rectifier tube and opted for a GEC driver tubes that were meant to be hard wired but were converted to conventional tube pins by Tubemonger. Those amps with that speaker are magic. But, they have significant limitations. Back in the day I augmented them with Decca (later Sequerra) ribbons and a few odd subwoofers. A single pair of Quads doesn’t quite cohere doing this but a double pair ought to. That was a "thing" back in the day.
I still enjoy the old Quad system for what it is and on certain music, they are incredibly "transparent" sounding but at the same time, almost act like a noise filter, eliminating some of the gremlins you might hear on a more revealing system. They also have a wicked impedance curve which makes certain amps unsuitable to drive them, and a tendency to "arc" if overdriven. (McCollum installed a protection device to prevent this).
I recommend that people get to hear a pair at some point in their lives because they are part of audio history. I think it takes a special kind of listener to appreciate them long term, though. For me, it is easy enough to go to the big system if I want to recreate a large presentation in more realistic scale, but for small scale works, they remain a marvel. The audio fora are rife with stories of people who owned, sold and then bought the old Quad again.
I get great satisfaction from this system, which in good part, I’ve owned for 50 years, even if it isn’t a complete "all-arounder" as systems go.
thanks.