It's hard to imagine a jazz unit with a more eclectic, demanding or refreshing repertoire than the L.A. Four. Performing at Charlie's for the first time last night, the group opened in typical fashion: Guitarist Laurindo Almeida first performed alone and then, one by one, his partners joined him on stage until the quartet was complete.

Almeida began with "Clare de Lune Samba," a delicately poised yet swinging nod to Claude Debussey. Then Almeida took turns with impeccable bassit Ray Brown in casting Gershwin's "My Man's Gone Now" in dark, somber tones.

Drummer Jeff Hamilton, by far the youngest member of the group, stressed the compatibility of the rhythm section with his own "Long John" before reedman Bud Shank, who played his alto sax while perched atop a bar stool, recaptured an earlier mood with a decidedly Latin look at "Watch What Happens."

While their individual contributions were impressive, the quartet's performance was even more so. Almeida's tranquil arrangement of a Villa Lobos piece contrasted sharply with the bright, dancing lines Shank forced from his flute on "Teach Me Tonight."

With a group as talented as this, it's hard to simgle out anyone for honors, but Brown's mastery of the bass can't be ignored. Even at his most inconspicuous, he was subtly assertive, underpinning his companions' work with flawless taste and execution. If last night's opening set had any drawbacks, it was that Brown wasn't featured often enough. The L.A. Four appear at Charlie's through Saturday.