Spoleto Festival's chamber music series typically goes through three phases, like many composers do: early, middle and late.

Each phase has a character and mood that corresponds to the moment in the chronology. Early in the chamber music series, everyone is giddy with excitement, glad to be in Charleston and reminded of the delights offered by this remarkable cast of musicians.

Then, for Program IV or thereabouts, a special guest steps in, perhaps a composer, perhaps a performer (this year it was singer Charlotte Helekant), and the enthusiasm matures. Later, perhaps at Program VIII, another new face appears, or a familiar face arrives anew (this year it was pianist Stephen Prutsman), reinvigorating an audience now accustomed to the palpitations prompted by these daily concerts. This is the mature phase.

The first concert of this last stage featured three wondrous pieces of Romantic-era music. The last, Brahms Piano Quartet in C minor, was a stand-out among all the music performed during the series' 11-program run. It featured Prutsman, violinist Livia Sohn and La Familia Diaz, Gabriela on viola and Andres on cello. It was a lush yet precise rendition that let the sentimentality in the music speak for itself. Brahms took 20 years to complete the piece, emcee Geoff Nuttall reminded us, probably because of his ambivalent feelings toward his friends, Clara and Robert Schumann, and his long-simmering infatuation with Clara.

Brahms' predilection for lush sentimentality always is tempered by his self-imposed adherence to classical forms and his careful rhythmic and tonal constructions. As a result, his music, especially his glorious chamber music, is a neat balance of heart and mind. In this quartet, though, the angst and passion come through clearly. It references Goethe's "The Sorrows of Young Werther." Werther, you may recall, falls in love with a woman engaged to another man, then befriends them both in order to remain close to the woman. Sound familiar?

It starts at a gentle trot, gets pretty feverish in the second movement scherzo then shifts key and mood for a lovely andante before ending with an allegro finale. Often, Brahms plays with hemiolas and compound meters, juxtaposing triplets and duplets, and this quartet is no exception. Other complicating devices include chromatic exchanges between players, swelling dynamics and moments of splendid homophony. It all sounds so Romantic! Yet it's all so carefully conceived and structured.

The musicians played it beautifully. I think next year there should be more Brahms in the chamber series.

Program VIII began with Verdi's String Quartet in E Minor, performed by the St. Lawrence String Quartet, who clearly delighted in the project and emphasized the cantabile nature of the piece. What makes it an important addition to the chamber music catalogue isn't its form (which is pretty standard) or its lyricism, but its innovative and effective application of bel canto operatic style, as well as Verdi's playful harmonic progressions. Listening to the work, one can't help but admire the coloratura and the melodrama.

The middle piece on the program was an early work by Arnold Schoenberg called "Ein Stelldichein," performed by oboist James Austin Smith, clarinetist Todd Palmer, brother and sister Diaz and Pedja Muzijevic on piano. It was a brooding, sorrowful piece that stretched the Romantic style and demanded of the players much grit and heart, which they gave willingly.

Program X was notable especially for the "Jazz Set" of Prutsman, though the chamber version of Haydn's Symphony No. 102 was a delight, and the Duo for Violin and Cello (the Diazes again) by Zoltan Kodaly was a commanding display.

Prutsman is one of those odd piano geniuses who can't be satisfied with just one genre, so a day after playing Brahms, he gave us two tunes, "Shadows" and "Dog," from his new jazz CD "Passengers."

He would not be contained. He started off relatively demur and polite, but soon got himself worked into a frenzy, playing crazy-fast runs up and down the keyboard and thumping his left hand rhythmically. He reached a point where the instrument simply couldn't handle it, yet he kept pushing - a spectacle indeed. The songs were firmly rooted in the jazz and blues idioms, but the impressive flourishes were entirely Prutsman's.

The final program of the series paid tribute to Todd Palmer, who has been performing in the Spoleto Festival for 20 years. He arranged an "Introduction, Theme and Variations" by Rossini for the occasion, which gave him the chance to sing on his clarinet like a diva. He sang beautifully, managing those quick melismas and arpeggios deftly and issuing forth a remarkably expressive tone.

The program ended with a performance of Mozart's masterpiece, the Clarinet Quintet in A Major, featuring Palmer and the St. Lawrence String Quartet.

"Mozart is famous for a reason," Nuttall noted. "He is really good."

The piece is really good, and the performance was really good. Palmer and the gang were tight, offering gorgeous pianissimos, elegant phrasing and tasteful rubato. It was Mozart as it should be played.