From A (Aviv) to Z (Zapp) and back again (Afiara), this year's Chamberfest has an extraordinary array of string quartets, 13 in all.

Despite the reduced number of concerts in this year's Ottawa Chamber Music Festival, it is probably the richest in this cardinal chamber genre than any previous one. The recordholder until now was the 10th festival, which called upon the services of 10 quartets from three continents.

Friday evening it was the Afiara String Quartet's turn to strut its impressive stuff with a program of Bartók, Haydn and Mendelssohn along with the music of two composers most have never heard of.

It opened with Pannonia Boundless by Serbian-American composer Aleksandra Vrebalov. It's a short, expertly crafted piece that made an excellent, if slightly dark, curtain-raiser. Certainly the Afiaras made effective use of it in that capacity.

Next was Haydn's Quartet in D, op. 76, no. 5. The opus 76 quartets are usually thought of as the composer's greatest chamber works, and there was nothing in this performance to undermine the notion. Of all the Haydn performances we've had this year, this was among the most idiomatic. The slow movement was lovely without being overblown.

It's hard to remember now, but 50 years ago the music of Bartók, and especially the string quartets, was considered impossibly complex and grotesque. Modern, in other words. No doubt some people still regard it that way, but their numbers are thinning out, thanks in part to performances and recordings of the last couple of decades that, like the Afiara's, find more logic and humanity in the scores, and express it with greater cogency.

The second half began with Mendelssohn's Quartet no. 4 in E minor, to which the Afiaras lent a compelling urgency that sometimes overwhelmed the score's considerable wit. There were also moments, happily few and brief, in which the urgency was replaced by haste.

The program ended with another short work, El Sinaloense by Severiano Briseño, a Mexican composer of the mid-20th century. It's a flamboyant and virtuosic bit of fluff, and ended the evening nicely.