A BOX of Sarah Vaughan records is like a Whitman's Sampler of sound. "The Pablo Years" collects the six albums Vaughan recorded for that label between 1978 and 1984 and confirms Gunther Schuller's evaluation, made during a Smithsonian lecture several years back: "Hers is a perfect instrument, attached to a musician of superb instincts, capable of expressing profound human experience, with a wholly original voice."

Of course, most people who hear Sarah Vaughan are simply reduced to applause, something they've been offering since she won an Apollo Theater amateur contest in 1943.

Vaughan's four-octave voice, the jewel that is perpetually polished by her rhythmic, melodic and harmonic invention, is presented here in a variety of settings. There's "Send in the Clowns" with the Count Basie Band, a pair of Duke Ellington Song Books featuring small units and big bands, an on-site Brazilian outing, and two intimate quartet sessions under the leadership of pianists Roland Hanna and Oscar Peterson.

The only real dud in the set is "Copacabana," a collection of mediocre Brazilian pop tunes that suffers mostly from the unfamiliarity of the material. After all, one of the joys in listening to Sarah Vaughan is hearing her work her magic on songs that are well- known and widely recorded.

The Ellington sets are particularly impressive, a swirl of small group pieces occasionally fleshed out with lush string arrangements and brass accents (though it's hard to beat the Basie session for sassy, brassy overdrive). The 21 Ellington tunes include his best-known works as well as seldom recorded songs such as "Black Butterfly" and "I Didn't Know About You."

Still, the quartet sessions (with guitarist Joe Pass as a common denominator) may be Vaughan's best showcase; they are certainly the most intimate and she seems to feed off that elemental interplay, wrapping herself around a lyric (or in the case of "Autumn Leaves," a wordless flight of vocalese) so that it's a seamless union. Vaughan may be a first-rate improviser, but she is above all a peerless interpreter of popular song who zeroes in on the emotional undercurrent of every lyric and weds it to vibrant performance. Over the years, Vaughan's voice has deepened slightly, her art immensely.

SARAH VAUGHAN -- "The Pablo Years (Pablo 2650- 101); at Blues Alley Friday through Sunday.