The Austrian H.K. Gruber is a friend and one of his favourite composers. "Gruber's brain and heart are in the same place," is his forceful testimonial. "He may write very complex music but it's always grounded in pulse and harmony. His roots might be in Schoenberg, Stravinsky and even the Beatles but, listen to just two bars, and it's unmistakably Gruber."
And so it is with Brett Dean. But when the three movements of the Australian's Dramatis Personae are titled Fall of a Superhero, Soliloquy and The Accidental Revolutionary, we know we have travelled far from the terrain of Haydn and Hummel.
Hardenberger laughs when the word "theatrical" comes into our conversation. No, he is not jumping around on stage; nor does he wear a Superman suit. "The first movement, though, is almost like film music but it goes wrong," he says.
"I try to overpower the orchestra with heroics and muscle, but it doesn't happen."
He sees connections between the second movement and Dean's operatic project Hamlet. There was crucial re-writing on this section of the score. "It was made longer and some beautiful moments extended. It's very hard to assess how a piece works until you play it in front of an audience. Then you can tell whether the electricity is there or not."
The third movement references a scene from the 1936 Charles Chaplin movie Modern Times in which the comedian inadvertently picks up a flag and waves it, unaware of its revolutionary implications.
"I quietly put out ideas that my friends and colleagues in the trumpets pick up and gradually the momentum grows. It's not singalong, for sure," he laughs, when I ask about possible audience response. "This is music that might shock and shake but that's important. Music, however beautiful, matters far too much to me to be just a museum piece. Why should we engage in an art form that only puts people to sleep?
"I don't want to be the sort of musician you can count on, like coming home to mother. I like being unpredictable."
You can hear the man in person when Hardenberger is interviewed by NZSO trombonist David Bremner in a pre-concert talk at 6.45pm.