Few artists have had as much trouble as Phoebe Snow in following up a spectacular debut album. Her four-octave voice has never been less than exceptional, but she has seldom matched the intuitive originality of that first effort.

For most of her show at the Wax Museum last night, she was an admirable interpretive singer; on a handful of songs, she showed flashes of her best instincts. Backed by a solid if unchallenging rock quintet, Snow sang every number--from Bob Marley's "Stir It Up" to her own "Stand Your Ground"--impeccably, usually ending with her patented falsetto wail.

A few songs went beyond mere good taste, however. An understated arrangement of "Into the Mystic," framed by mandolin and acoustic guitar, allowed Snow to take the vocal into the dreamscape of Van Morrison's lyrics. She gave a crisp swing to "Point of View" and finally cut loose with uninhibited growls and shouts on "Blue Monday." Yet it was her first hit single, "Poetry Man," that was still most impressive in its fragile romanticism.

The Persuasions have their on nights and their off nights, but the opening set last night was one of their best. The a cappella quartet was meshing perfectly and took advantage of the good sound system to give special prominence to Jimmy Hayes' booming bass arpeggios. They transformed everything from the Oak Ridge Boys' "Elvira" to the Everly Brothers' "All I Have to Do Is Dream" into their own brand of testifying doo-wop. Preaching the gospel that everyone is secretly a doo-wop singer, lead vocalist Jerry Lawson invited more than 30 people from the crowd to help sing the rousing finale, "All Night Long."