Lunchtime concerts as a spin-off from the partnership between the Riverfront and the young professional orchestra Sinfonia Cymru are working well.

In addition to turning out regularly as a full-blown chamber ensemble, the orchestra's members also combine in smaller numbers for the venue's First Wednesday series of monthly recitals.

These offer kaleidoscopic variety but are rarely as concentrated as this one, in which eight musicians turned out to play the Britten Phantasy Quartet in F (oboe and string trio) and Beethoven's illustrious Septet in E flat.

Britten's Opus 2 provides little cushioning between the four instruments, the strings often agitated and the oboe rhapsodising or playing mournfully above them. Early exposure, then, which Rhys Watkins (violin), Lucy Nolan (viola), Peggy Nolan (cello) and oboist Kathryn Bennington dealt with admirably in terms of both structure and the predominance of the wind soloist, a voice if not in the wilderness then in a wonderful Brittenesque world of its own.

Ms Bennington was replaced by Sebastian Pennar (double bass), Craig Macdonald (horn), James Thomas (bassoon) and Lee Mottram (clarinet) for the Septet.

As was often the case with Beethoven, this work is cast in a familiar mode but is exceptionally treated. It's a serenade but not as we know it. The invention is unstoppable, the traditional roles for each of the wind trio frequently subverted and the length sub-symphonic.

For the players, the trick is to convince that something serious is going on in architectural terms while at the same time remaining upbeat - and be ready with undiminished bounciness after the motion has slowed. These musicians demonstrated how.