This foursome recorded two of the most original vocal-jazz albums of their time, 1979's Playground and 1981's Last Year's Waltz, both for ECM and out of print. Kuhn's songs -- some tongue-in-cheek, some with free-association lyrics, some quite somber -- were unlike any in the standard repertoire. And Jordan's ability to interpret the material and improvise put her on equal footing with an uncommonly sensitive trio. Shortly after ECM released Last Year's Waltz, the band broke up -- until bassist Swartz proposed a reunion.

During their first set last Saturday, the quartet quickly re-established their old rapport. They played only one of Kuhn's songs, the opening "Gentle Thoughts"; but the mutual support and interaction among band members -- chemistry that's sometimes difficult to recapture -- was back from the first notes.

Jordan's playful way with a song demands quick reflexes. And "All or Nothing at All" and "Gentle Thoughts" were enlivened by her expert phrasing. She dragged one line, then impishly hurried through another. On "Haunted Heart" and especially on her duet with Kuhn on "My Funny Valentine," she inflected phrases downward with a breathy sob and used dynamics -- a crescendo on a word for emphasis or a sigh that withered away to add emotional depth -- to keep her delivery fresh and surprising. The same quicksilver play of emotions, elastic sense of time, and subtle inflections marked her improvising on "Where You At?"

Jordan is one of our greatest living jazz singers, but she's not this band's only asset. Much of what she sings is inspired by the rest of the group, and vice versa. Kuhn responds to Jordan with enveloping chords or expertly timed counterlines. Jordan might pick up one of Swartz's interjections or respond to a sudden surge from Moses. Moses might circle lightly around the beat, then lock into a groove that kicks Kuhn into high gear. It's a band whose enjoyment of one another and delight in performance communicates to audiences and lets them share in the fun.

When Jordan left the stage to the trio, the tempos and volume picked up, but the focus remained on group interplay. On Steve Swallow's Latin-tinged "Ladies in Mercedes," Kuhn's impressionistic harmonies predominated as he guided repeated figures up and down the keyboard in a beautifully paced solo. His reharmonization of "Stella by Starlight" revitalized a well-worn tune. Swartz, who was exceptionally responsive and inventive in the ensembles, also shone on the ballad, in a harmonically sophisticated solo full of dazzling fast lines and dark blues riffs.

The music reflected the ways in which the players have changed and grown. Kuhn continues to perfect his piano-trio playing on albums for independent jazz labels, and his left hand is now sturdier, his lines even more probing and varied. His latest trio recording is due on ECM in mid March. Jordan has established a fruitful partnership with bassist Swartz, recording several duets with him, and their interplay has become second nature. Bob Moses, now a New England Conservatory professor, has reduced the number of his jazz performances in favor of his Afro-pop band Mozamba, and his interjections of funk and African rhythms created the biggest changes in the group's dynamics. But aside from Moses's newfound rhythmic interests and the group's greater reliance on standard repertoire, it was as if these players had never parted. It's time to reissue their old albums. Or maybe record a new one.

-- Ed Hazell