Australian Chamber Orchestra/ Tognetti, Wigmore Hall, London

The 17 strings of the Australian Chamber Orchestra directed by their dynamic young lead violinist Richard Tognetti made a strong impression at the 2002 Proms for their spontaneity and power - not least in an arrangement of Janacek's String Quartet No 1, which actually seemed to enhance its needle-sharp articulation. Their latest concert to a Wigmore Hall packed with their enthusiastic compatriots, similarly culminated in a Tognetti arrangement - this time, of Szymanowski's String Quartet No 2, Op 56.

A comparatively compact three-movement work dating from 1927, this subtly combines the Polish master's languid chromaticism with a bracing folkloristic element out of Bartok. And, unlike a string quartet from the Viennese classical period, it again positively blossoms in string-orchestra enhancement. The wide-spanning melodic line of the work's crepuscular opening revealed just how sensitively these players could inflect an insinuating line, while the stamping folk fiddle sonorities of the central scherzo almost overwhelmed the modest Wigmore acoustic in their rasping resonance.

However, the Szymanowski only arrived at the end of a long bill that begun already 10 minutes late with Tognetti announcing a complete revamp of the programme.

Out went the promised Arvo Part; in came a short piece by the exiguous, Luxembourg-born Australian, Georges Lentz entitled Te Deum Laudamus, and sounding in its drones, clusters and gently diatonic pulsings like a distant cousin of Gorecki's "Symphony of Sorrowful Songs".

The rest of the first half was all-Baroque, starting with Vivaldi's Concerto in C, RV 117 into which the ACO pitched with such gutsy iterations as almost to convert it into instant Michael Nyman. Yet the readings of Corelli's Concerto Grosso in D, Op 6 No 7, and of Handel's Concerto Grosso in A, Op 6 No 11, were wonderfully alive and various in their response to these kaleidoscopic multi-movement works. Whereupon the liquid-toned prize-winning French flautist Emmanuel Pahud appeared to play the Concerto in C, Op 7 No 3, by the 18th-century violin virtuoso Jean-Marie Leclair. This centred on an adagio full of delicious French harmonic suspensions but its outer movements proved disappointingly bland.

As, in the end, did the short modern concerto Pipe Dreams, an ACO commission by the contemporary Australian Carl Vine, with which Pahud opening the second half. Comprising a bustling moderato opening, a wanly melodious middle section teetering in the direction of kitsch and a more abrasive fast finale, it proved pleasing enough in a mildly modern if singularly anonymous way.

But this quite outstanding ensemble surely deserves something altogether richer and more demanding to exercise its full artistry.