Spring has sprung and March, still roaring like a lion, has departed, which means that concert seasons are slowly winding down.

Last Tuesday, the Brentano String Quartet closed the season for the Honolulu Chamber Music Series with engaging performances of Mozart, Ligeti and, with the addition of cellist Mark Votapek from the Honolulu Symphony, a Schubert quintet.

It is not technique so much as style and interpretation that identify professional ensembles, and the Brentano quartet presented a distinctive sound featuring clean, slender timbres that lent a classical style, paired with intense interpretations of more romantic inclinations. The combination was overly respectful of Mozart, at home in Ligeti, and perfectly suited to Schubert.

Mozart's Quartet K.387 in G major, the first of six dedicated to Haydn, featured Haydn's signature witticisms: sudden pauses, odd harmonies, "gotcha" fake endings, surprise turns, syncopations, even slapstick musical humor. The work may have been composed during the classical era, but it is less "classical" than a wry commentary on classical balance and beauty. The only real surprise was why the audience wasn't laughing.

One reason might have been that the Brentano quartet played the piece as "High Art," homogenous, rarefied, exquisite, beautiful, which made the music more perfect, but also more distant. One does not laugh aloud at "High Art." The question is, what was Mozart trying to convey?

Those ethereal realms of perfection include dangers — ever present in Mozart — of transparency: every minuscule deviation from perfection glares. On Tuesday, fleeting but irritating fluctuations in intonation, rushed silences, and pushed cadences intruded on what was nonetheless a very good performance.

Particularly thrilling were exquisitely light runs by first violinist Mark Steinberg, a perfectly executed moment of angst before falling back into the theme in the first movement, and the melting lyricism of the third movement.

Ligeti's Quartet No. 2, in some ways even more classical than the Mozart, communicated with timbral effects rather than melodies, and the Brentano quartet conveyed every nuance with all the intensity so characteristic of mid-20th century classical music. Their playing was evocative and vivid, from lacewing delicacy shattered by cacophonous outbursts in the first movement, to tick-tocky mechanical precision in the third, to the lull of buzzing flies in the fifth.

Schubert's Quintet in C major, D.956, composed only weeks before he died, revealed surprising ties to Haydn, Mozart and Beethoven, almost as though the piece were summing up his life.

If true, Schubert must have had an inordinately rich life, because the Quintet lasted a good hour, a certain encore-killer however deserving the performance.

Perhaps it is needless to say that the piece offered gorgeous melodies, irresistible rhythms that had the performers half dancing in their seats, and effervescent Viennese elegance spiced with gypsy influences — those are, after all, what Schubert is known for.

Guest cellist Votapek added a new voice to the Brentano quartet, literally and timbrally. Although he played as one of the ensemble, and beautifully at that, he stood out with a tone rounder, deeper and more open than that of his colleagues. That might be expected with any addition to an established ensemble, but it was especially noticeable with the Brentano quartet because the group has developed the blending of tone so desired by professional groups.

All in all, Tuesday's exceptional performance left the audience looking forward with anticipation to the next season.