When it comes to fathoming the musical tastes of yuppies, no record label can rival the success of Windham Hill and its unique roster of composer-musicians. Unfortunately, when the West Coast label showcased three of its acts at the Warner Theatre Saturday night, the results were uneven at best.

Perhaps it would be unfair to comment on the opening set by a trio led by composer-instrumentalist Mark Isham, since one of the minicomputers he uses to trigger electronic elements in his orchestrations failed to work early on. Nevertheless, the finale, an affectionate and acoustic (by necessity) tribute to Fats Waller, was a refreshing change of pace from the highly synthesized and dispassionate music that preceded it.

Windham Hill founder Will Ackerman followed with a thoroughly enjoyable and relaxed collection of acoustic guitar solos and duets. His ballads were generally built around attractive arpeggios in slowly moving chords, while his faster pieces were much more percussive, ringing with clipped rhythms, blue notes and sympathetic harmonies in the bass.

Headlining was Shadowfax, a sextet that operates much like an electronic chamber group, often fusing elements of rock, jazz and classical music. At their best, the band's arrangements were colorfully imaginative, with Chuck Greenberg's flutelike lyricon casting a gentle spell. Nearly as often, though, the music seemed far too deliberate, bereft of any real emotion or excitement.