The Beethoven Op. 132 String Quartet and the Bartok String Quartet No. 4 are pieces that ensembles build whole programs around. Put them back to back on the same program, and they can seem almost an embarrassment of riches. But that’s what the Shanghai String Quartet did in its appearance at the Freer Gallery on Thursday — and its members did it so well that, with the welcome space of an intermission between the two to absorb and decompress, you came away exhilarated.
The more loudly passionate movements of each of these quartets came off with power and appropriately hard-edged attacks, but the centerpieces of both are their long, slow middle movements that offer huge challenges to balance, clarity and restraint. These proceeded so serenely and inevitably that one longed for each reappearance of the rising theme of the Beethoven and the shifting textures of the Bartok, and almost hated to have the movements end. And with a violist (Honggang Li) and a cellist (Nicholas Tzavaras) who play magnificent-sounding instruments and who can let their lines emerge almost magically, passages where inner voices that don’t usually dominate surfaced and gave the music an unexpected sort of “aha” new look.