Väsen, a Swedish acoustic group, comprises three musicians with a singular sound, a playful yet accomplished interplay that seems to defy the laws of physics, an intensity with a great sense of humor, and modernity rooted in tradition. The group, which has toured together for nearly three decades, plies a five-string viola, a 12-string guitar and a nyckelharpa (a “keyed fiddle”) for a sound that is deeply rooted in the traditions of Swedish folk music. All three are instrumental virtuosos in their own right, and together they form a unique supernatural being. To experience Väsen is to witness ensemble playing at its finest. There’s a playfulness to their music, a joyousness in making exciting new arrangements of centuries-old tunes.