Paul Griffiths’s candy-coated booklet-notes employ flowery ad-man doublespeak – ‘How times have changed. How a recording can change them’ – to persuade you that pairing György Ligeti with Samuel Barber is a sound piece of linked-up programming. ‘Both composers belong to the world of performance,’ he tells us. And as that stunning revelation sinks in, Griffiths comes back for more. Ligeti and Barber both dealt in ‘the gesture of lament’.

Ligeti’s First Quartet, subtitled Métamorphoses nocturnes, was written in 1954 under the thumb of a totalitarian regime. When Barber wrote his String Quartet in 1936 – from which he extracted the slow movement as a standalone work – he was living a charmed existence of awards and commissions, and would soon be championed by Toscanini. People are naturally free to contextualise music as they like; but the only insight I gained was to be reminded that things that exist at the same time in the same world might have absolutely nothing to do with each other, and for sound cultural reasons.

Which is a pity, because the Budapest-based Keller Quartet handle the individual demands of both composers thoughtfully. A cleaner, cooler, more controlled Barber I doubt you’ll find: zero warbling vibrato, no emotive hard-sell. But jammed in between Ligeti’s quartets, in this unhelpful context, the truth is that Barber’s tonality sounds generic. Ligeti’s Second Quartet, written in 1968, from its opening sculpted out of bat-range harmonics to the obsessively twitching mechanisms and chit-chattery lines (check out tr 1, 3'56" to hear how well the Kellers deal with the rhythmic anti-flow), remains mysterious and fantastically unknowable; as if you want to turn it into a concrete structure to slow down its patterns, to walk among them, to get the measure of its enormousness. The Barber is a closed, settled book; Ligeti is difficult to read.