The Merit School’s Gottlieb Hall was the perfect setting for Sunday’s performance of the Avalon String Quartet; the intimate space cradled the Avalon’s lush and dynamic readings of three late works of Romantic giants. The Quartet began with Schubert’s "Quartettsatz" in C minor, a single movement distillation of all the agitation, sweetness, and tension that the composer was capable of writing. The Avalon employed aggressive and sensitive playing equally; the Quartet’s cohesion was quickly evident. The lusty opening chords of Beethoven’s Quartet in E-flat Major, Op. 127, announced the composer’s presence in the room; the Avalon marked the occasion and dispatched them with precision. Cheng-Hou Lee’s ringing cello and wide vibrato propelled his mates through the theme-and-variations format of the second movement, while the Quartet displayed its agility in the manic scherzo. The group navigated the mood swings of the last movement with effective pianissimo echoes, subtle cues, and artful pauses. To close, famed clarinetist, and Merit alumnus, Anthony McGill joined the Avalon in Brahms’ Clarinet Quintet in B minor. Catapulted into national recognition after his performance with Itzhak Perlman and Yo-Yo Ma at the Inauguration of President Barack Obama, and currently principal clarinetist of the Metropolitan Opera Orchestra, McGill blended into the Avalon’s rich fabric as if he was a regular member of the group. Brahms sets up the clarinet’s opening melody, and McGill’s syrupy tone cast a spell over the audience, a prelude to his performance of the Adagio. McGill’s intoxicating sonority, particularly in the low register, combined with muted string tremolo to mysteriously veil the exotic melodies that Brahms might have heard from a cimbalom in 1890s Vienna. The mood shifted dramatically to the third movement’s nimble presto, the clarinet and strings chasing each other into a tumultuous finale of variations. Brahms gracefully returns to a clarinet flourish that similarly began the piece, ending with a swell and decrescendo that the ensemble held just long enough—an indicative ending to a tasteful and impassioned performance not soon forgotten.