The Klenke Quartet play modern instruments but are assiduous in their application of historically informed performance practice. Vibrato is employed so sparingly that if I happened upon these performances on the radio, I might at first think they were played on period instruments. With intonation that’s consistently spot-on, the ensemble’s gleaming, fine-spun tone not only beguiles but allows for a textural clarity that can enhance the brilliance and exhilaration of certain passages. Listen in K593 to the dazzling virtuoso interplay in the development section of the opening Allegro (starting at 5'12"), and how the precipitously cascading figures are buoyed by the punchy syncopated accompaniment. Occasionally, first violinist Annegret Klenke’s sound projects so fiercely that it throws off the internal balance in her crucial dialogues with the first viola (which I assume is played by the quartet’s Yvonne Uhlemann rather than guest Harald Schoneweg, although the booklet doesn’t specify).

Tempos are consistently brisk, often giving a sense of lively banter in the outer movements – try the finale of K515 for an especially delightful example. Indeed, the Klenke seem to have taken to heart Mozart’s famous dictum that his music should ‘flow like oil’. Even the slow movements have a feeling of urgency. In the magical Adagio of K174, for instance, there’s a slightly breathless quality that induces an unexpected feeling of disquiet. By contrast, the Chilingirians with Yuko Inoue (CRD, 11/07) are only a hair slower yet convey a rapt, moonlit atmosphere.

If only the Klenke were as meticulous in their attention to Mozart’s dynamic indications as they are in adhering to historical performance techniques. One might not think of Mozart as taking especial care over such details in his scores, yet the very first page of K174 abounds with carefully placed forte piano markings in the second violin and second viola’s chugging accompaniment – and not the common fp that’s an immediate loud to soft but one where volume alternates by crotchet. The Nash Ensemble observe these conscientiously, producing a joyous, pulsating energy, while the Klenke don’t make much of them at all. Nor do they make much of the dramatic forte outbursts in the opening Allegro of K593, while in the Adagio they underplay the sudden piano after the opening two-bar crescendo, robbing this surprise sotto voce gesture of its operatic effect.

I’m puzzled, too, by the Klenke’s oddly nonchalant phrasing at the beginning of the first movement of K515, music Charles Rosen views as ‘of a chromatic bitterness and insistence that can still shock by the naked force of its anguish’. The Menuetto, on the other hand, is masterfully done: lean and aching, with a Trio that allows in a few precious rays of sunshine. I hear far more pain in the Adagio than the Klenke seem to, particularly in the second theme with its stabbing sforzandos and throbbing semiquavers. And then there’s the extraordinary slow introduction to the finale. ‘Nothing closer to an ultimate despair has ever been imagined’, Rosen writes of it, although here it sails blithely along. The Nash, at more or less the same tempo, delve far deeper into this passage’s tormented heart.

Indeed, although I retain a profound emotional allegiance to the Budapest Quartet’s mono LPs I fell in love with more than 40 years ago – and whose latest CD reissue by Sony was lauded by Rob Cowan – the Nash’s dramatically alert and stylishly expressive accounts have also won a place in my heart. Both sets move and charm me in a way that the Klenke, for all their lucidity and finesse, never quite manage.