Ax and Stoltzman delight

It’s hard to recall a more congenial pair of touring classical musicians than pianist Emanuel Ax and clarinetist Richard Stoltzman. The two seemed to be greatly enjoying themselves at Royce Hall on Thursday night -- bantering playfully as they made their entrances, arms resting on each other’s shoulders as they exited, easily fielding questions from the audience after the concert with quick one-liners.

Stoltzman remains one of the most, if not the most, expressive clarinet soloists in the world, and he seems to bring something extra out of Ax. Together, they probed the varied corners of Debussy’s Premiere Rhapsodie to an amazing degree -- Stoltzman leaning soulfully into the opening phrases as Ax suavely veiled his tone with the soft pedal, heightening the later contrasts with frisky, sprightly flights. After Ax’s refined take on Debussy’s “Estampes,” they tackled some German meat-and-potatoes, Brahms’ Sonata Opus 120, No. 1, with Stoltzman exploiting his ever-changing, now-rich, now-fierce lower register.

While the first half of the program might have tilted toward Ax’s European core, the second half was definitely Stoltzman country -- tonal, eclectic, often playful and folksy American music. Leonard Bernstein’s Clarinet Sonata -- written at age 23 -- is the earliest piece of his repertoire that has caught on, with the distinctive syncopated Bernstein accents of the future in full bloom in the second movement.

Ax and Stoltzman selected four of Robert Beaser’s six “Souvenirs,” mostly jaunty reworkings of folk songs -- including the tune that became the union anthem “Which Side Are You On?” -- and an incongruously solemn epilogue titled “Ground O.”

Lukas Foss’ Three American Pieces was similar in vein, an idealized view of Copland Americana that may have sounded nostalgic even when it was written, during World War II.