For two solid hours at Wolf Trap on Saturday night, interrupted only by applause and standing ovations, Joan Armatrading again proved to be among the most powerful and passionate singers in pop music, as well one of the more insightful lyricists today writing about relationships.

Her voice, a husky alto that often soared to a finely tuned soprano, was a marvel in itself. Sensuous, spirited and soulful, there was seemingly nothing beyond its reach, including the defiant rockers "I Love When You Call Me Names," "Drop the Pilot" and "Free." The last was one of several tunes drawn by the Caribbean-born singer from her new album, "Hearts and Flowers," the others being mostly tender musings. As a romantic balladeer, Armatrading puts most of the competition to shame, but she was at her best when she took a cue from her own "Show Some Emotion" -- one of the evening's highlights -- and sang of love, heartache, jealousy and remorse with no holds barred.

Another plus was her five-piece band. Recently, Armatrading has been producing her albums with a light touch, but in concert she still values the punch of a guitar-and-sax-driven ensemble that vibrantly weds elements of reggae, rock, pop, soul and jazz.