Essential: a masterpiece of progressive rock music.
When speaking of Progressive music, in general I prefer studio albums to lives because the studio work allows the artists to put as many details as they want in their music.
This album is the exception. It's first of all a rock album. The quality of the sound is "Fit for purpose" in the sense that you know clearly that it's live music and this is the kind of sound that a rock live must have.
A case of deja entendu here, since I reviewed these performances when they originally came out. I enjoyed them then and still do, for both artists offer wit, affection and agility. One can at times think the sheer force and passion of Martha Argerich's personality a bit too obvious, not least in the C major Sonata, where Maisky characteristically sounds smoother and more persuasive.