Here's a world beat dilemma for you: Nusrat Fateh Ali Khan is one of the world's great singers, but his qawwali music is intended for Sufi Muslim religious ceremonies in Pakistan. How can Khan whose explosive high-tenor scatting and keening are usually accompanied by a tiny, reedy organ, a smattering of percussion, and an enthusiastic male chorus be made palatable to the general listener? Mustt Mustt shows one way: ''sweetening'' the sound of Khan's music very gently with synthesizers, electric guitar, and electric bass. Purists will object, but this album, using mildly funky bass and atmospheric rockish tendrils of sound, creates a cool rhythmic context for the hot-blooded Khan. When the spirit moves him, this plump, cherub-faced Pakistani erupts into long arcing gasps of passion, punctuated with rapid chattering and corkscrew swoops. Here that spirit seems more relaxed and secular than on Khan's other albums. Mustt Mustt is a good appetizer for those meatier entrees.