The 40-year-old Haydn seems to have conceived his Op 20 quartets as a showcase for his newly won technical and expressive virtuosity in the medium he made his own. Endlessly unpredictable in topic and texture, these three works alone range from the gypsy antics of No 4’s Minuet and finale, via the pathos and contrapuntal cerebration of No 5, to the al fresco exuberance of No 6’s opening Allegro. As on their disc of Nos 1 3 (A/16), the cosmopolitan Chiaroscuro Quartet, playing on gut strings with minimal vibrato, combine refined ensemble and intonation with an audible delight in the music’s richness and inspired subversiveness. Like all the best Haydn players, including the two period-instrument quartets listed below, they are constantly prepared to be surprised by the composer’s teeming invention.

If you know these works well, you may initially raise an eyebrow at some of the Chiaroscuro’s interpretative choices. Haydn marks the first movement of No 6 Allegro di molto e scherzando, though you’d barely guess it from a performance in which whimsy and delicacy rule over scherzando high spirits. The robustly sinewy Mosaïques and the fleet, mercurial London Haydn Quartet inhabit a different world here. From its secretive opening, with the four players sounding like a viol consort, the Allegro di molto first movement of No 4 is also unusually flexibile and innig. I wouldn’t always want to hear it like this, though there are many rewards in the eloquent shaping of phrases and the timing and shading of cadences. Controversial, too, is the fugal finale of No 6, where the Chiaroscuro eschew the comic implications of the leaping main theme and find an unexpected wistful tenderness in the music: it’s touching, and certainly valid on its own terms.

If the Chiaroscuro’s refinement and subtlety can sometimes short-change Haydn’s animal spirits, they tear into No 4’s lopsided gypsy Minuet, relishing the raw resonance of the open strings; and, playing fast and loose with the tempo (repeats, as ever, are a cue for new thinking), they gleefully milk the finale’s antic mayhem. The F minor, No 5, is compelling throughout: from the elegiac breadth of the opening Moderato, shaped in long paragraphs, through Alina Ibragimova’s sense of fantasy in the siciliano Adagio (vindicating an unusually mobile tempo), to the fugal finale, where the players’ tense, contained sotto voce aligns it with the mood of the opening movement. In sum, the Chiaroscuro, sometimes controversial, always illuminating, nicely complement their two period-instrument rivals. All three versions, each with its own distinctive insights, demand concentrated and, as the 18th century put it, ‘philosophical’ listening. Which is exactly as it should be in these inexhaustible works.