Paul Simon may have introduced this South African group to the United States when he borrowed their warm a cappella sound for Graceland, but in the more than 20 years since the release of that album Ladysmith Black Mambazo [2] has made a name for itself. In 1993, the soulful singers traveled with their country's soon-to-be president Nelson Mandela as he accepted the Nobel Peace Prize, and over the years they've received 13 Grammy nominations, including one for the 2008 recording Ilembe: Honoring Shaka Zulu. Tomorrow night, the vocalists fill the Boulder Theater with their uplifting African sounds. Wed, Mar. 4, 7 p.m. Boulder Theater [3]; 2032 14th St., Boulder; 303-786-7030 $35-$39