London Concertante, Wigmore Hall, London

Established some 15 years ago, London Concertante is a chamber group of strings led by Adam Summerhayes that gives about 100 concerts a year in venues across Britain and beyond. Might one gently suggest, after their latest Wigmore visit, that this is, currently, a few too many? Throughout the evening there was a suspicion of strain, of capable players too tired to focus upon the niceties of the choice repertoire they were delivering.

The best playing came in the neo-Mozartian luxuriance of the Prelude to Richard Strauss's Capriccio, a one-movement sextet in the middle of which the curtain rises to the same music from backstage a clever upbeat to an opera that proves to be about its own creation. Here the phrasing had a grace and breadth, the sound a real glow.

But things tensed up in Brahms's String Sextet No 2 in G. While the ebullient second-movement trio and scudding finale went well enough, the first movement got off to a not-quite-in-tune start, while the coda of the variation-form slow movement that sudden sunset effulgence sounded merely tremulous owing to the intense style of rapid string vibrato this group cultivates.

At which point we were offered their encore, so as not to spoil the mood at the end of Schoenberg's tone-poem sextet, Verkläte Nacht, of the second half. We got a dour little tango by Astor Piazzolla.

As for Schoenberg's hyper-romantic evocation of sin and redemption, this was undermined from its slow start by hints of rhythmic impatience, and though there were moments of excitement and stillness in the ensuing narrative, the moonstruck transformation ran into serious intonation trouble towards the end.