What a feast of glorious and diverse music has been presented this year at the Canberra International Music Festival. That there is just one performance of each specially arranged work makes each concert a treasure.

One has to love Rossini for his exuberant approach to composing the Petite Messe Solennelle expressed in his forthright conversation with God: 'Who would believe it? Among your disciples there are those who sing out of tune! Lord rest assured: I affirm that there will be no Judas at my supper and that mine will sing in tune and with love your praises.' Roland Peelman presented the work in its original form for 12 voices (The Song Company and Friends) accompanied on piano (Neal Peres Da Costa playing the Erard Grand Piano) and harmonium (Aaron Chew playing the 1912 Packard Harmonium). The 12 "Cherabim" as Rossini referred to them, brought to life a score that combines ethereal harmonies with operatic gaiety – an entertaining combination. The distinctive physicality of performing on historical instruments as much as the unique sound produced contributed to the success of this concert – transporting us to an era in which keyboard players had to use quite different techniques to produce music. With its wonderful Steampunk bellows and strident growling – sometimes braying – chords, the harmonium added an elemental underpinning to the performance.

It would be difficult to find a better blend of voices than those of the vocal ensemble on Sunday evening. The Song Company provided beautifully balanced ensemble work, duets and trios. Guest Alto Maartje Sevenster gave an unforgettable performance with a rare lightness and warmth in a vocal range that can sound darker and heavier. Tenor, Robert MacFarlane sang with irresistible joy, unleashing operatic flourishes for the benefit of both God and the audience.

In Concert Nine, The Streets of Madrid, The Boccherini Trio – Suyeon Kang, violin; Florian Peelman, viola and Paolo Bonomini, cello – demonstrated why they are an ensemble to watch in the coming years. They have mastered a uniform lightness and elasticity in their combined sound, matching the voicing of their respective instruments to play as one. Mozart's Divertimento in E flat major is a demanding work, and at first there was a tendency to rush the entries as each instrument spoke. By the adagio, tuneful focus was established and the six movements unfolded without losing the lift and warmth. For the performance of Boccherini's Night music from the Streets of Madrid, the trio was joined by Andrey Lebedev, guitar; Rohan Dasika, double bass; Anna McMichael, violin and Alfredo Bringas, castanets. What a treat to hear this suite live, with the cello lifted up and placed sideways to be plucked; the violins, viola and bass duelling with savage bowing and the spirited castanets driving the music ever onward.

What might have been an unfortunate mish-mash of composers, traditions and genres was in reality a splendid exploration of synergies between musicians and Baroque masters in the concert Scarlatti meets Handel meets Bach. Seldom does the contemporary classical concert scene encourage soloists to improvise spontaneously in the way that earlier eras did. James Crabb, accordion; José María Gallardo del Rey, guitar and Joseph Tawardros, oud seized the opportunity to transform themes by Scarlatti and weave them between each other into a new and interesting fabric after proving their virtuosic credentials with solo performances. Who but Crabb could invite such nuanced phrases from an accordion?

The program was nicely paced, beginning with Peres da Costa performing Bach's Concerto nach Itlaienschem Gusto in the central position of the Fitters' Workshop, and two delicious, complementary Scarlatti sonatas: in D minor, K29 and D major, K353 interspersed with Gallardo del Ray breathing Latin spirit into two Concert Studies: No.4 by J.S. Bach and No.11 by C.P.E. Bach. The young, accomplished Jonathan Lee coaxed the Knud Smerge replica chamber organ to recreate the delicate pipe organ sounds of Handel's era in the Chaconne in G Minor and Concerto in B Flat.

Full credit to Roland Peelman and the musicians who took up the challenge of this musical journey of exploration and shared the treasure they discovered with the audience.