Twice Grammy-nominated harmony duo The Milk Carton Kids released their third album, Monterey, to rave reviews, garnering their second Grammy nomination, this time for “Best American Roots Performance” for their song, “The City of Our Lady.” A refreshing alternative to the foot-stomping grandeur of the so-called “folk revival,” an understated virtuosity defines The Milk Carton Kids. Follwing their 2014 Grammy nomination for Best Folk Album for their previous release, “The Ash & Clay,” The Milk Carton Kids won Duo/Group of the Year at the Americana Music Awards in 2014. Their featured performances and interviews in T Bone Burnett & the Coen Brothers’ concert documentary, “Another Day/Another Time,” were hailed as a highlight by press and fans alike. Cultural purveyors from Garrison Keillor to T Bone Burnett to Billy Bragg have hailed the duo’s importance among a group of new folk bands, both expanding and contradicting the rich tradition that precedes them. Yet while some of the band’s many accolades reference a specific genre, the duo quickly transcends those tags with clear inflections of jazz, classical, even the dark lyricism of modern “alternative.”