There’s a fine performance of the Sinfonia concertante here. But the obvious selling point is Berlin Philharmonic viola player Diyang Mei’s transcription of Mozart’s last and, for many, best-loved concerto. Mei broadly follows the reconstruction of Mozart’s original for basset clarinet, with those extra low notes. Just as the Brahms clarinet sonatas acquire an added duskiness in their viola versions, so the viola tends to darken the overall tinta of Mozart’s concerto. It’s hard, of course, to hear Mei’s transcription without the overlay of the original in your mind’s ear. I miss the clarinet’s vivid colour contrasts between registers and, especially in the finale, its capacity for bubbling high spirits. The viola, happiest in its middle and lower ranges, is never a natural bubbler. For all Mei’s skill, rapid detached notes on the viola simply can’t replicate the sparkling ease of tongued notes on the clarinet. And the leaps and plunges of the Adagio’s fantasia-like central section, fashioned to exploit the basset clarinet’s oily chalumeau register, sound unidiomatic on the viola.

The transcription is most convincing in passages of sustained lyricism: in long stretches of the first movement, sounding that much more plangent on the viola, and in the hymnlike theme of the Adagio, where Mei’s husky, burnt-umber tone is selectively coloured with vibrato. Mei’s sensitivity, his subtle variety of articulation and phrasing and his command of the long, singing line could hardly be bettered. Despite a few touches of frisky ornamentation, the finale emerges as unusually reflective – aptly, some might say, for Mozart’s last completed instrumental movement. The scaled-down orchestra, based on just 11 strings, accompanies with chamber-musical finesse, though it’s a pity the six violins are all bunched together on the left rather than being divided antiphonally.

Beefed up by two additional violas, the orchestra launches the Sinfonia concertante with a perfectly gauged tutti, taking note of Mozart’s maestoso marking. From their floated initial entry, Mei and his Berlin Philharmonic colleague Noah Bendix-Balgley make a predictably well-matched pair of soloists. While their forward balancing rather militates against a true pianissimo, there are many felicities in a performance marked by poetic shading and elegant dovetailing. In the Andante, flowingly paced, the soloists respond to and intensify each other’s sorrowful lines with unforced eloquence. And if other players bring more devil-may-care élan to the final Presto, the Berliners’ graceful, relatively contained performance is rewarding on its own terms.

For all my reservations about the transcribed Clarinet Concerto (perhaps I should try harder), I’m glad to have heard it. In the booklet note Diyang Mei hopes that Mozart’s ‘Viola Concerto’ will find a place in the repertoire alongside the Sinfonia concertante. It would certainly be difficult to imagine anyone making a more persuasive case for it.