Scotland seems to specialise in musical groups in the smaller size category (and I am not thinking of Scottish Opera, which is currently shrinking before our eyes). The Scottish Chamber Orchestra has made a good name for itself and encouraging reports regularly come down from the North about the still smaller Scottish Ensemble, originally founded in 1969.

With a core membership of only 12 string players this group is poised between the private world of the string quartet and the more standard concert repertoire of the chamber orchestra. There is nowhere to hide when there are only a dozen musicians on the platform, so performances tend to be fearsomely concentrated.

The Scottish Ensemble has a new compact disc of music by Britten to promote and its Wigmore Hall appearance on Monday started with a commercial. The first work on the programme was Britten's early song-cycle Les Illuminations, sung (as on the CD) by Toby Spence. In theory, his bright, agile, light tenor should be a perfect match for the sprightly playing of the Scottish Ensemble strings, but that fails to take account of the way that small numbers of musicians tend to make a large amount of noise. Spence spent a lot of time struggling to summon sufficient decibels, when what we really wanted was a truly chamber-sized performance - exquisite, subtle, with every word of Rimbaud's hypnotic poetry easily audible.

A couple of smaller string pieces went better: Bruckner's Adagio from his Quintet in F comes across like one of the magisterial slow movements from his symphonies after a spell on the Atkins diet; and Tippett's Little Music for Strings is in effect an offshoot from his other larger, more memorable, string works around the war years.

Then it was down to business. Give Schönberg's Verklärte Nacht to the strings of the Berlin Philharmonic and what comes out is likely to be an overweight romantic wallow. Here the Scottish Ensemble came closer to the discipline of the composer's sextet original. There was no fat on the sound - just clarity, lean textures, imaginative detail and a sense that not a note was being wasted.

Tel 020 7935 2141