The Master Singers of Lexington is a 30 voice SATB chamber chorus directed by Adam Grossman. The best way to sum up the group’s four decades may be the vast repertoire of music it presents, which ranges from major classical works by familiar composers to modern compositions written specifically for the group and performed for the first time. The Master Singers delights its audience with spirited and little-known ballads and Broadway tunes at its annual Pops concerts, but has also performed Handel’s Messiah, Bach’s St. John Passion and Mass in B Minor, and Mozart’s Requiem. A few years ago it premiered an original work by local composer Pamela Marshall, The Future of Life, based on writings by Harvard biologist E. O Wilson. Rehearsals are in Lexington on Wednesday night. Please see the group’s website for audition information.