This is one of my favorite recordings of the piece, from the Pro Arte Quartet, which was quite famous around the world in the 1920s and 1930s, when they were in residency in the Royal Court of Belgium, and their tours brought them around the world.
The recording is from 1935. The violinists were Alphonse Onnou and Laurent Halleux; violist Germain Prévost and cellist Fernand Auguste Lemaire. They were joined for the recording by cellist Anthony Pini.
Does anybody happen to have the version with Casals at his festival? I remember hearing it once on an old LP. A professor of mine played it for me when I was an undergrad student, and I remember being mesmerized by the humanity of the recording. It seemed to me that there was an overall feeling that Casals was guiding and inspiring the other players. And there were really truly time-stopping moments in the recording. I would be very grateful if anybody could share it!