There's also a wild card - a name many pop-music consumers and a few classical types have heard about, but perhaps haven't heard: Esperanza Spalding.
The majorly Afro'd jazz singer/double bassist, only 28, will be the first jazz artist to open the Carnegie Hall season, at a moment when her inside-cool factor is at its peak. Only recently has she penetrated the mainstream; two years ago, the West Coast-born, New York-based Spalding won the best-new-artist Grammy over Canadian heartthrob Justin Bieber, whose fans were left asking (vehemently), "Esperanza who?"
Geffen was first captivated by her on the 2012 Academy Awards telecast: "She was singing 'What a Wonderful World,' and it was so beautiful. It's a song we associated with a particular voice [Louis Armstrong's], a particular way of inflecting the words, and she made it into ... a separate reality that was just as beautiful and just as valid."
Rehearsals (some of which are taking place early this week in Philadelphia) are closed to the media, and Spalding hasn't given advance interviews. But in the past, she has talked about her view of the jazz world as one of inherent adventure.
She has performed at the Academy of Music in years past as part of the annual Marian Anderson Award gala (though not with the orchestra). Classical music can't be too far from her thinking, considering that songs on the Carnegie program are drawn from her album title, Chamber Music Society.
"We knew this would be a calculated risk," said Geffen. "But we know that every year at the Academy Ball, the Philadelphia Orchestra performs with nonclassical vocalists and artists. If there's any orchestra that makes sense for something like this, it's the Philadelphia Orchestra."
Those guests have tended to be veterans - Rod Stewart, Billy Joel - who aren't new to symphonic pops appearances. Spalding's numbers with the Philadelphia Orchestra required new, Carnegie-commissioned orchestrations by Gil Goldstein, of Spalding's own "Apple Blossom," Leonard Genovese's "Chacarera," and Dmitri Tiomkin's "Wild is the Wind."
"The orchestrations look very interesting," said Nézet-Séguin. "The whole orchestra is in an active role," as opposed to the sonic-backdrop role symphonic orchestras often play in such situations.
"There's something so all-embracing and curious about Yannick," said Geffen. "He seems to feed off other people's excellence. . . . He seems not to draw the boundaries so clearly between 'real music' and 'popular music.' "
The conductor definitely brings respect to the pairing with Spalding.
"The bass-playing is astonishing. The voice is such a special thing, which makes a very unusual character, a very authentic jazz groove," he said. "Certain people have a genius at being their own person. Here is the Philadelphia Orchestra at the top of its field. It needs to collaborate with others . . . and she's at the top of her field."
A skeptic might call the program a "crossover" concert, a term often associated with a failed fusion of genres that's neither here nor there. "That's why I prefer to talk about collaboration," said Nézet-Séguin, "and the fact that we build bridges between different kinds of art."
Some U.S. orchestras believe financial salvation lies in greater emphasis on pops concerts. Nézet-Séguin is not one of them: "I don't think the future of orchestras rests on those shoulders. That's only a small part. The bigger gesture is to be more open, to open our doors and open our ears."
The biggest barrier between Spalding and the orchestra may not be a matter of genre; many of the Philadelphia musicians play jazz on the side, and she is a wide-reaching musician who encompasses echoes of classical and hip-hop. But her art feels fundamentally intimate, particularly in contrast to the ultra-public, large-scale symphony orchestra.
Geffen claims not to be worried: "Part of being a professional musician is being able to adapt quickly. I just know that she's not going to disappoint."