Having exercised his seigneurial rights to choose exciting players (including himself) and beloved repertoire, Rockport Music Festival’s Artistic Director Barry Shiffman shared with Thursday’s rapt full house, signal accounts of Mozart, Grieg, and Brahms masterpieces.

Despite the ensemble’s ad hoc status, seconds into the Mozart Quartet in E-flat Major, K. 493 (1786), Paul Huang, violin; Barry Shiffman, viola; and Nicholas Canellakis, cello; had jelled into what hereafter should assume the moniker MozzArts Trio. Pianist Alessio Bax, whom we have admired from his work at New England Conservatory, expanded it into a stellar foursome.

At once we opened our hearts to the group’s perfection of sonorous enunciation and artistry of phrasing. Limpidity of impulse from the piano framed the gorgeous lines from the strings, as nuance and expressivity gleamed. Flexibility of tempi allowed briefly dark auguries to yield at once to child-godlike delights. Exquisite ppp phrase endings in the piano and unanimously inhaled swells from the strings began the tender delicacies of the luminous Larghetto. Lively without a trace of flippancy, the Allegretto smiled with string-of-pearls scales from the piano, poignant pauses, and operatic songfulness from all in a well-plotted but improvisatory amalgam.

Grieg’s Violin Sonata No. 3 in C Minor, Op. 45 (1887) opened with the force of an orchestral tornado. Huang’s violin emoted with a staggeringly juicy and generous tone. He reveled in the technical demands as well as the full-bore outpourings of poetry. Bax alternately responded and led with alacrity. In the Allegro molto ed appassionato, the partners redefined musical virility. Huang took up the Allegretto espressivo alla romanza, a serene Norwegian song without words, in a realm of serenity, as the golden hour suddenly began to paint the sky above Sandy Bay. The second theme danced with irresistible luster. A ppp reprise wooed us for the pinpoint harmonics at the finish. After an animated argument vigorously tossing gestures among friends, the Allegro animato, morphed into a Carmenesque idyll with unabashed smoldering. A recap led by Bax, whose gigantic tone never turned harsh, built to a conflagration as the sky beyond responded in Technicolor glory.

Composed in 1853-4 and revised in 1889, Brahms’s Trio in B Major, Op. 8 for piano, violin, and cello opened with a profound dialog between the cello and the piano. (Tovey reminds us that “Brahms made hardly any changes [in his revision] to the first 80 bars or so, except for omitting little interjections by the violin that he supposedly only included in the first version to meet a desire of Joseph Joachim). We witnessed a very grand and probing dialog between Bax and Canellakis which rose from a growl to a roar. One of those immersive moments that put us in a metaphorical condition, it summoned Thomas Mann, “Deep is the well of the past. Should we not call it bottomless?” As the movement progressed, every surprising turn of phrase felt inevitable. The brief fugal moment resolved itself with piety.

Of royal dimensions, the rhapsodic Scherzo: Allegro molto sparkled with clarity and elegance as well as signal passion. The two string bards entwined exuberantly over the piano’s string-of-pearls filigree. As the cello and piano doubly embraced the closing melody with ineluctably deep and romantic grace, one wonders how Clara could have denied herself to Johannes. The players went attaca into the wonderfully patient and serene Adagio. Canellakis smoldered, as the ensemble maintained steadiness and tension at a vanishing pppp. No one drew a breath at the rapt close. Sharp elbows and irresistibly delivered rhythmically complex accents characterized the Allegro, aside from the cello’s second theme in which Canellakis projected passion through tears. Bax gave forth spectacularly lucid arpeggiations as the collective passion rose like the unfolding of a new golden age.

Lee Eiseman is the publisher of the Intelligencer