There is danger in trying to do justice to the musical memory of Luther Vandross: The stakes are high, with little margin for error. Vandross not only sang like an angel -- with a buttery tone, a dancer's rhythmic aplomb, and unabashed, infectious emotion -- but he was a superb arranger and producer whose studio work almost invariably flattered his colleagues and burnished the legacy of soul music. Add in the subtle but unavoidable racial resonance -- for whatever reason, Vandross's songs were embraced by the black community far more pervasively than anywhere else -- and the performances on "So Amazing: An All-Star Tribute to Luther Vandross" bear more freight than your typical posthumous slap on the back.

Some fascinating dynamics compose this star-studded album. Aretha Franklin, who owes her early-'80s career boost to Vandross's shrewd, empathetic production skills, and whose rendition of "Amazing Grace" at Luther's funeral in July is already the stuff of legend, gives everything she has during a magnificent vocal tour de force on "A House Is Not a Home" -- and relentlessly suffocates the song, a cardinal sin Vandross never committed. Donna Summer, who worked with Vandross in the late '70s, reprises his '90s hit "Power of Love" with a churning, shiny glaze that successfully alludes to his early affinity for disco.

The results of the commercial machinations behind the project are equally unpredictable. Who could imagine that the powerhouse pairing of Beyonce and Stevie Wonder (on the title track) would fall so flat? What were the odds that actor Jamie Foxx would nearly hold his own in such robust company, with a modest but credible version of "Creepin' " that proved he can do more than moan like Ray Charles for a moment at awards-show podiums? Who would guess that hearing Wyclef Jean's rambling preamble to "Always and Forever" would make us pine for a Fugees reunion but that hearing Babyface's Babyfaced rendition of "If Only for One Night" would make us pine for Vandross's innate sense of adventure?

Given that Vandross was such a kindred spirit to divas, the sheer depth of distaff warblers on "So Amazing" is not so surprising. Mary J. Blige shows why she's the Queen of Hip-Hop Soul with a beautifully tenacious take on "Never Too Much," and Fantasia is left clinging to her "American Idol" fame with a pleasantly forgettable cover of " 'Til My Baby Comes Home." Others remain true to character: Patti LaBelle as the sassy granny via a tear-it-up version of "Here and Now," Angie Stone as the soulful earth mother on "Since I Lost My Baby," and Alicia Keys as the precocious kid on the creatively chosen, artfully rendered Marvin Gaye tune "If This World Were Mine."

Perhaps inevitably, the best vocal performance on the disc probably belongs to Vandross himself, whose elegant ballad "Anyone Who Had a Heart" is interpolated into one of those production studio duets with Elton John. Hearing Sir Elton's blustering tenor against Luther's lithe voice is the sonic equivalent of watching Muhammad Ali school a succession of palookas in the ring during his heyday. As rewarding as "So Amazing" is in places, you're better off picking up a copy of "The Best of Luther Vandross." He'll forever rest in peace.

Luther Vandross, shown in 2002, deserves better than "So Amazing" provides. The singer died in July.