The reason I switched to Maggies almost 10 years ago was the fact that, of all the speakers I've heard so far, these were giving me the best loud-vs-quiet sounds ratio. What I mean by that is when the orchestra is playing swelling crescendos, I want to still be able to hear clearly a tiny, quiet triangle ringing all the way in the back, in the farthest orchestra row. A pair of Magnepan MG-1 IMP were giving me that kind of presentation, which I found totally disarming. So I had to own them.
Lately I kept hearing how Quad 57s excel at exactly that -- a phenomenally low sound floor. So I had to hear them. Luckily, a friend had a pair just recently refurbished, so he was kind to organize an afternoon session of listening to Quads. He told me to bring any LPs or CDs of my choice, and to take my time. Which I did.
My overall impression is that Quads are similar to enjoying the old Dutch masters. In contrast, listening to my Maggies reminds me of enjoying Van Gogh's paintings. In a way, there are similarities between the two camps -- both are Dutch ;) Both Quads and Maggies are planars, using a flat membrane to produce sound. And that's pretty much where similarities end.
Maggies drastically differ in scale from Quads. Despite the fact that the host was pairing Quads with a subwoofer, the bass was woefully inadequate compared to my Maggies. Quads were giving me a very intimate overall experience, with a soundstage that resembled a doll house. In comparison, my Maggies are giving me pretty accurate real life soundstage. Drums look like real life drums, singers are standing in front of me with their real height (between 5 foot 5 inches and 6 feet tall).
Overall, Quads are definitely way more resolving. I'm hearing more details, longer decays, but at the expense of coherency. At certain points, it all sounded like a collage, instead of a coherent performance by the musicians playing on the stage.
Maggies seem to sacrifice some of the finer details for the sake of cohesion. Everything seems to gel with Maggies, while with Quads it's all scientifically, analytically correct and pin-pointed. But the 'sauce' to tie in all those accurately reproduced instruments is sometimes kind of absent.
Quads are amazing in that, for the first time ever, I had a listening experience that is like a combination of loudspeakers and headphones. Also, on top of being more resolving, Quads deliver warmer, silkier sound. But sometimes that warmth is at the expense of liveliness. Some of the sparkle that I'm getting from Maggies seems to vanish when Quads are playing.
In conclusion, Quads are awesome for intimate listening sessions. A small acoustic combo, breathy vocals, string quartets. Those types of recordings seem to make Quads shine. For other, more muscular type of music., I'd prefer Maggies.
Bottom line, I need both pairs in my house. Quite impractical, but I think it would be worth it.
Now the hunt begins for a good pair of vintage Quad 57s!