Carpe Diem Quartet is masterful in both classics and modern works

The string quartet field is so crowded that every group is looking for some hook or cachet to set itself apart. A number of these quintessentially classical ensembles have branched out into pop, jazz, bluegrass and world music, with decidedly mixed results. Until Saturday evening, I had never heard a performance by one of these multilingual quartets where the classical repertoire was delivered at a level that was competitive with the finest traditional groups. But the Carpe Diem Quartet, appeari...