A composer, arranger, pianist and occasional singer, Klein began his craft in childhood in Argentina. When his father gave him a piano at age 11, he promptly began writing songs, inspired by the legendary Argentinean composer Astor Piazzolla. Klein attended Berklee College of Music, where his intention to study classical music gave way to his passion for jazz. His colleagues at Berklee—many of whom came from South America—provided the framework for what would eventually become Klein’s main musical voice, the Big Van large ensemble (later called Los Guachos). After graduating from Berklee, Klein moved to New York City and quickly became associated with Smalls, a jazz club where he established a weekly engagement with his 17-piece Big Van band. Smalls was critical in fostering young artists that would ultimately be some of the most influential voices of modern jazz.
Klein scaled the band down to a more streamlined 11-piece unit, known as Los Guachos (roughly translated, the bastards). The band developed in residencies at Smalls and, later, the Jazz Standard. Sunnyside Records soon released two CDs by Los Guachos: Los Guachos II (1999) and Los Guachos III (2002), and Klein is still with this label. Since moving back to Argentina in 2000 with his wife, Klein has recorded with local musicians and has released a series of critically-acclaimed CDs with Los Guachos including: Live in Barcelona (Sunnyside, 2005), Filtros (Sunnyside, 2008) and his latest, Carrera (Sunnyside, 2012). Other important recordings include his work as a composer and/or arranger on Solar Return Suite (with the MIT Wind Ensemble), Domador de Huellas (Sunnyside, 2010), Bienestan (Sunnyside 2011) with Aaron Goldberg and Miguel Zenon’s Grammy-nominated, Alma Aldentro.
Klein plays regularly with some of the most outstanding musicians in the jazz community, like Chris Cheek, Miguel Zenón, Bill McHenry, Jeff Ballard, Ben Monder, Aaron Goldberg, Carmen Canela or Jorge Rossy. In addition to teaching composition in Buenos Aires, Klein has given master classes and seminars throughout Europe, including the Jazz Institut Berlin, Sibelius Academy in Helsinki, Jazz Schule Basel, and Le Mirail in Toulouse.