Judging a diva by her shoes is a perfectly legitimate litmus test: Self-presentation is part of her art and who she is. So when the jazz singer-bassist Esperanza Spalding made her entrance on the Verizon Hall stage Tuesday night, her bright-pop-of-color stilettos made multiple statements.

Those shoes told you to get ready for wild cards. But the fact that she eagerly went barefoot during one of her songs — in a program with the Philadelphia Orchestra and the Carnegie Hall NYO2 ensemble — suggested that superficiality is fun, but only that. Her multilayered, hairpin-turn jazz comes from a highly cultivated place, not creative whims.

Spalding was the guest star of the concert, and was initially positioned between ballet suites by Copland and Falla. Her equipment and side musicians presented logistical issues, though, so she ended up performing first — in a free concert that attracted a well-filled hall that had some intermission departures, whether because the Spalding fans got what they came for or because the symphonic fans feared they would not.

The attraction and the challenge of Spalding's performances are their density, arranged for her multi-octave voice and quicksilver sensibility. The music doesn't follow tidy, prescribed forms but goes where it expressively needs to go.

Her song "Ebony and Ivory" was framed by the singer and her two backups in a high-velocity monotone rap full of witty social commentary. What came in between was all over the place, and I mean that as a compliment to her logic-stretching riffs and highly original sense of what comes next. The range, agility, and richness of her singing voice are like Cleo Laine on the best steroids ever invented.

Oh, yes, there was a symphonic collaboration here. In some songs, the orchestra was silent for the majority of the time. At times it supplied opening splashes of sound that focused your attention on what was to come. In other songs, it added welcome layers to what was already there. In "Apple Blossom," a piece about life and death, the orchestration brought a welcome weight to the darker moments but was no more essential to Spalding than her shoes.

NYO2, a child of Carnegie Hall's Weill Music Institute, consists of musicians ages 14 to 17, with instructors that include Philadelphia Orchestra veterans who were sometimes sprinkled among the younger musicians and sometimes in a half-and-half configuration.

The NYO2 group was mostly on its own in Copland's Billy the Kid ballet suite, with its Americana atmosphere and oddly unconvincing descriptive effects. Conductor Giancarlo Guerrero drew a solid performance.

The combined NYO2 and Philadelphia Orchestra in Stravinsky's The Firebird were suitably exciting.

Falla's Three-Cornered Hat suite under Guerrero was a clean break from the super-suave Charles Dutoit approach from years past. I've always loved the music, and Guerrero balanced its ebullient, folksy atmosphere with its modern rhythmic sensibility, finding a surprising kinship with the less congenial music of the early 20th century.