The 1990s oeuvre of these South African musical ambassadors is gathered on the two-disc The Ultimate Collection, which opens with “Halala South Africa,” a 1990 tune written in celebration of the country’s newly paved path to post-Apartheid democracy. The acappella voices (led by Joseph Shabalala) are clear and strong, with harmonies blending seamlessly, joy infusing every note. The group’s strengths are reaffirmed on “Diamonds On The Soles Of Her Shoes,” from 1986’s Graceland—Ladysmith buoys Paul Simon’s watery vocals, making “Diamonds” a jewel—and “Once In A Blue Moon” (sung with British pop group Lighthouse Family in 1999). The Chillout Sessions boasts remixers Soul Drummers, Temple of Sound and the South African trio Nicky Blumenfeld, Dumi Dhlamini and Concord Nkabinde. The doodlers approach Ladysmith’s songs with the respect they deserve, never overwhelming the voices raised to the heavens with the blips of man-made earth. A good thing too: why mess (too much) with perfection?