Bach, Mozart and Beethoven: one could be forgiven for thinking that an evening featuring only these three canonic figures was a step back from the usually adventurous programming by the Australian Chamber Orchestra. Needless to say, these choices were less mainstream than they appeared at first sight: two of the works were new arrangements, and even the third had new cadenzas. Aside from the satisfying chronological ordering of composers, the concert was bookended by fugues. And not just any fugues – works that are the summative contributions by Bach and Beethoven to this most cerebral of genres.

Excerpts from Bach’s Art of Fugue have been heard in ACO concerts before: in 2013, Contrapunctus I-IV were performed by a quartet of strings unobtrusively backed by the organ. This time, the same initial four parts of the work were given in an entirely new arrangement for a full complement of strings and winds. We don’t know for certain what forces Bach had in mind, or indeed if he envisaged any specific performance, so not even a purist could object to its adaptability.

Although not a period ensemble, the orchestra captured something of the effect of Baroque performing practices by restricting the use of vibrato. Variety was achieved by means of articulation: in Contrapunctus I the tone was deliberately glassy, Contrapunctus III was very short and detached, while in Contrapunctus IV pizzicato was employed. During the course of this last number, one became conscious of someone humming; gradually the rest of the performers joined in, singing along with their parts in half voice like timid Swingle Singers. At the end players and patrons alike were left with a smile on their faces.

Mozart’s Violin Concerto no. 5 in A major was the non-fugal intermission between the two Bs. As soloist, Richard Tognetti was typically accomplished, although his decisions about when to use vibrato were somewhat whimsical. The second movement was taken at quite a brisk pace, but was none the worse for this. Perhaps the highlight of the performance was the Hungarian/Turkish episode in the final movement, which was delivered with enormous gusto by soloist and orchestra.

While Bach’s music can be (and has been) arranged for every instrumental and vocal combination under the sun, adapting Beethoven’s music for other forces is a much more debatable practice. It could be argued that the medium Beethoven was writing for is integral to how he composed: for example, what was conceived as a piano work remains marked by its pianistic qualities. Beethoven’s string quartets, which contain some of his most private and concentrated musical thoughts, are radically different from his orchestral compositions, which were crafted as impressive, public pieces. Consequently some might question the propriety of scaling up the forces from four players to a string orchestra. However, even if one had no ethical qualms about doing this in principle, there are formidable practical difficulties involved in achieving a musically satisfying result with larger forces.

There were moments of both loss and gain in Tognetti’s arrangement, and these were not always in areas I might have expected. The moments of intimacy were not ruined by the larger forces: in particular, the delicate fifth movement Cavatina was a sheer delight. Long a favourite of the orchestra (they’ve used it in part in at least two other projects, the film Reef and the Timeline show), the lyrical lines of this movement were treated lovingly, and the ‘beklemmt’ section was breathless in its concentration. Similarly, the fugitive Presto second movement didn’t lose its breathless quality through the increased forces. By contrast, the exaggerated breaths Beethoven marked in the Alla Tedesca fourth movement were smoothed out.

In the opening movement, the coordination of the strings in the first shocking outburst of fast music was immaculate, although the extra forces counter-intuitively made the climaxes less rather than more impressive here. The one serious miscalculation in the arrangement came at the start of the third movement. The main theme here is supported by a light bubbling figure in the cello, but in this rendition, the addition of the bass (even though it was used sparingly thereafter) made it sound leaden-footed.

Where the orchestral forces really came into their own was in the infamous Grosse Fuge, the original finale Beethoven wrote, and then detached as a separate work. A ne plus ultra of violence and dissonance, the restored finale was given a full-blooded performance, with the opening section sounding emphatically aggressive. The following G flat major section was an oasis of calm, and provided blessed relief between the frenetic material flanking it. The more dance-like later sections were fulsomely lyrical. The players rose magnificently to the demands here, and in an unfair fight (Bach’s work was only performed in part), Beethoven won the fugue-off this time.