Rosanne Cash is one of the few performers working in the pop, rock and country mainstream whose synthesis is more an artistic triumph than commercial strategy. Her show at the Wax Museum last night was not only a showcase for her sultry balladeering and the seamless instrumental work of her band, the Cherrybombs, but also for some of the best material in contemporary country music. While Cash's singing has plenty of old-fashioned country feel, her songs and those of her husband, Rodney Crowell, are full of the emotional and sexual ambiguities of modern relationships.

You don't get pop songs more brilliant than her "Seven Year Ache" or "Ain't No Money," and Cash's reflective, almost tranquil delivery granted her material the special emotional poignance that songs gain when you feel an artist has lived them. Unlike most pop stylists, Cash doesn't try to tear a song apart all night. Instead she holds it close to her heart and puts it in the same spot for the audience.

The Johnny Seaton Band opened the show with an aggressive set of obscure rockabilly material from the '50s. While Seaton carries far too many of the theatrical and vocal mannerisms of Presley, he shakes and sings with so much energy that he puts most of his songs over on sheer physical enthusiasm. Especially impressive was his guitarist, Jay Montrose, whose blistering lead work recalled rockabilly aces James Burton and Roy Buchanan.