There is no doubt that there is the sort of energy on this disc, particularly in the Mendelssohn, that is hard to find anywhere else. Although the speeds are sprightly, they are neither too fast nor injected with a synthetic energy, but rather in keeping with the authenticity of performance practice that underpins the Chiaroscuro Quartet’s musical integrity. They play on gut strings tuned to a lower pitch than the standard modern concert pitch of A=440, and this ensemble is without a doubt a trailblazer for the authentic performance of High Classical chamber music.

It is excitingly difficult to attune the ear to their unique sound, and the process of doing so allows listeners to accustom themselves to a strangely eerie sound world that is as rich and varied in colour as any ensemble chasing a warmer, more romantic identity. Every harmony is heightened, every voice within the beautifully blended corporate whole given a more distinctive edge. There is, though, a jitteriness in some of the Mozart that comes across less as a hazard of the historical performance and more as a simple unevenness of line. It is disquieting in the Andante in particular, because the lack of contrast between the simple sweetness and troublesome greyness that are unmistakably written into the score impoverishes the movement (and some of the quartet as a whole) of its Haydnesque character and consequent delightful frustration of structural norms. None of that, though, is evident in the performance of the Mendelssohn, which brings out with crystal clarity its Beethovenian influences and is as electric as it is elegant.