Though their history is steeped in the Hungarian—they formed in the ‘80s while attending the Franz Liszt Academy of Music—the Keller Quartett actually casts a tremendously wide net, offering up thoughtful, approachable readings of John Dowland (“I Saw My Lady Weep”) and an urgent and impassioned performance of Barber’s String Quartet, Op. 11. Their Schnittke chamber works are serious, with eerie upper strings and affecting attention to drama; taking on Bach, they illuminate the fabulous inner-mechanisms of his counterpoint in string arrangements of the timeless and mercurial The Art of the Fugue.