WINDHAM HILL'S most popular performer is jazz chart-W topper George Winston; his romantic piano solos recall Keith Jarrett but with stronger melodies and simpler structure. The label's most innovative performer is Michael Hedges, whose unorthodox attack on the acoustic guitar has opened up a new vocabulary for that instrument. With more than a dozen acts now, Windham Hill offers great variety.

Liz Story's solo piano album, "Solid Colors" (Windham Hill C-1023), bears the influence of Winston, Bill Evans and Jessica Williams. She even includes Evans' "Peace Piece" as "homage to its composer." She firmly strikes short, melodic phrases with her right hand, while she rolls soft arpeggios with her left. Using short and long pauses as punctuation, she restates the theme again and again in different variations. Only occasionally does she use chords for a contrast in texture. This balance only works when the melody is truly striking, as it is on the title tune, "Bradley's Dream," and on "Pacheco Pass" and "Hymn." When the melody is less than striking, there's nothing to save her piano-playing from becoming mere mood music.

Alex de Grassi makes the folk-jazz hybrid work especially well on his third album, "Clockwork" (Windham Hill C-1018), because his roots in folk music are so strong. Originally inspired by Pentangle's "baroque-folk" guitarists Bert Jansch and John Renbourn, de Grassi has extended their two-voiced style into more open-ended jazz explorations. Working from the cyclical progressions of folk music, de Grassi keeps a repeating figure going in one guitar voice, while another guitar voice takes off on a jazz elaboration of the melody before returning home to it.

On "Clockwork," this tension between folk gravity and jazz tangents is expanded by a long list of guests who include label mates Scott Cossu (on piano) and Chuck Greenberg of Shadowfax (on reeds). This tension is wound tightest on the title cut, where de Grassi's intricate, highly condensed guitar figure pulls against Greenberg's lyricon digressions. Side 2 is devoted to the five-part "Bougainvillea Suite." The first three parts are guitar solos with de Grassi's repeating figures occasionally bursting forth into florid embellishments. On the last two marvelous sections, de Grassi is joined by the three supporting members of the David Grisman Quartet for some bluegrass-gypsy-jazz picking that is as lively as it is intricate.

One of those guests from Grisman's band is fiddler Darol Anger, who has just released a duet album with his pianist-wife Barbara Higbie: "Tideline" (Windham Hill C-1021). Higbie has a strong reputation for her work with the Robin Flower Band and Saheeb (an eclectic quartet that also includes Anger). "Tideline" is obviously the joyful offspring of many hours playing at home together. There's no dominant voice; the equal give-and-take yields the close rapport of tight harmonies.

The tonal contrast between Anger's slippery violin (in the gypsy style of Stephane Grappelli) and Higbie's percussive piano (in the ECM style of Steve Kuhn) is milked for all it's worth in the six compositions by Higbie, the three by Anger and their closing collaboration. On the title cut, Higbie sets up a driving piano riff only to have Anger's violin slow it down. Eventually the violin rises above the piano in soaring, sustained lines only to subside into a rhythmic figure so Higbie can be released for her own free-wheeling improvisation. So it goes in all the pieces; no solo lasts too long as each spouse readily gives way to the contrasting response of the other.

A similar give-and-take is present on "Element" (Windham Hill C-1020), the duet album by pianist Ira Stein and oboist Russell Walder. It's no coincidence that this album bears the deep imprint of the popular pastoral jazz group Oregon since Stein studied with Oregon guitarist-pianist Ralph Towner and Walder studied with Oregon oboist Paul McCandless. "Elements" is not a pale imitation of a Towner-McCandless duet, so much as a welcome extension of the Oregon tradition. Stein wrote all six compositions, including the 11-minute title cut. All six works display a patient but persistent curiosity. It is the rich tone and elegant control of Walder's oboe, though, that reward Stein's musical explorations and the listener's patience.