As Teodor Currentzis remarked about recording Beethoven’s symphonies, there is a danger, even in sets of such exceptional character as this one, that powerfully individual performances may diminish one another by proximity. The view from Scafell Pike is hardly less momentous, satisfying or arduously attained for standing in the lee of Scafell itself.

The harmony of each musical vista is achieved by imaginative means. Assessing the cycle’s two previous instalments (9/18, 5/19), Richard Bratby welcomed the training of focus on a particular movement, like a landmark. In Op 18 No 5 it’s the variation third movement that acquires a centre of gravity. Launching the theme with pure tone like a skiff on a lake, the Casals Quartet sail through the variations in a spirit of playful serenity, anticipating the celestial and rustic visions of the Harp Quartet, the Pastoral Symphony and the Missa solemnis.

Until very recently, minimal vibrato (or none) was deployed by quartets as an expressive device, to chill the bones of a phrase or to lift its eyes heavenwards. Now, measured on a scale of expressive vibrato, it’s the other way around. Pure tone is the lingua franca of the Casals Quartet’s Beethoven, singing with drooping wings like an Italian madrigal in the graveside introduction to the finale of Op 18 No 6 while also imparting a gentle, Biedermeier nostalgia to the central Andante of Op 131 and a refreshing simplicity to the second section of the Grosse Fuge. The eruptions of Op 95 naturally generate more heat in the phrasing and fingering and, in the hands of the Casals, this is the quartet that most uncannily anticipates the breakdown of diatonic harmony with the Second Viennese School.

However, this is not Beethoven-playing that shakes a fist at the listener. For ‘character’, read characters: there are five individual personalities at work. Leading the Op 18 set and otherwise playing second fiddle, Abel Tomàs Realp seems to skate with daredevil confidence on a hair’s breadth of tone. Vera Martínez Mehner leads the Cavatina of Op 130 with admirable humility – the Beklemmt section ushers in a further intensification of collective grief rather than the lead mourner’s ecstasy of grief commonly encountered – but otherwise the microphone catches a quartet of temperaments distinct from, say, the Hagen Quartet’s notable unanimity of musical thought and gesture.

I like especially the Casals’s account of Op 131, fearless and unsullied by irony, but Op 130 is presented as the culmination – the ‘apotheosis’ – of the whole cycle, more spaciously conceived in proportion than its companions. The raw nerves, the adrenalin-fuelled accents and positive energy of the Quartet’s Beethoven style are channelled into a reading that achieves a notable integration of motivic development from first movement to last – the Grosse Fuge – with Beethoven’s alternative presented very much as an elegantly wrought second thought looking back to Haydn and the world of Op 18. Recent, more disruptive approaches to Op 130 from the Elias (Wigmore Hall Live, 3/17) and Belcea Quartets (Alpha, 8/13) demand attention, and I won’t be throwing out the LaSalle and other old favourites. The Casals, however, present a compelling yet familiar picture of Beethoven, generating tension and taking a forensic approach to detail in the manner of a modern police procedural.