I’ve been trying to put my finger on what it is about the Elias Quartet’s interpretative style that’s so powerfully affecting, and I think I’ve distilled the answer to a single quality: fearlessness. Virtuoso daring is perhaps the most obvious manifestation. The finales of Op 18 No 5 and Op 59 No 3 are absolutely brilliant – the former bubbling with joy and the latter suggesting the giddiness of an opera buffa overture – with the adrenalised energy sustained from first notes to last. Or turn to the Scherzo of Op 18 No 6, where they negotiate the accents and syncopations so deftly, and at such a clip, that the effect is akin to arrhythmia in a racing heart.

I also admire the unflinching way the players tackle even the most difficult, exposed passages, as in the first movement of Op 59 No 3, where leader Sara Bitlloch makes no attempt to soften or prettify the high-lying figure at 2'12" and simply strides through with gritty assurance (and spot-on intonation). At every turn, it seems, the Elias put projecting the music’s character above all else. In the slow movement of that same quartet, for example, they home in on its obsessive tone, not by being rigid or metronomic but instead through ruminative suppleness. The finale of Op 131 moves at a relatively measured pace, yet how desperately they claw its jagged lines. It’s a terrifying reading, a more dogged journey than the usual wild ride – although this grim determination throws the consolatory lyrical passages into especially sharp relief.

The Elias are riveting, too, in the tumultuous Allegro of Op 59 No 2, seizing upon the score’s many silences as avidly as the notes themselves, so that all the surprises are, in fact, surprising. Listen at 1'42", where Beethoven suddenly makes the pulse unclear; it’s clearly meant to be momentarily disorienting, and that’s exactly how the Elias play it. They’re rather less convincing in the first movement of Op 135, however. On the page, at least, this music also moves in fits and starts, but in this case the various pieces need to be fitted together rather than chopped apart. It’s the only disappointment in these two volumes, and the Elias redeem themselves with a reading of the slow movement that rivals the sublimity of the Busch Quartet’s reference recording (Warner Classics, 2/16). Sara Bitlloch applies portamento strategically (and memorably) throughout these performances, but the way she slides through the opening phrases here is especially exquisite.

Indeed, all of the slow movements are extraordinary. Note, for example, the fluttering accompaniment in the third variation of Op 18 No 5’s Andante cantabile, so gorgeously delicate it almost upstages the melody (listen at 4'37"). The Adagios of Op 18 No 6 and Op 59 No 2 are both broadly paced yet flow so naturally; there’s not even a hint of beat or bar line. And the expansive fourth movement of Op 131 is wondrously elastic – the Adagio passage (beginning at 8'53") throbs with such gentle tenderness, I had the sense I was feeling the beating of Beethoven’s own heart.

There’s no question this is a Beethoven quartet cycle of remarkable daring and individuality. As with the previous volumes, the sound is vivid and immediate, and includes applause.