[Read about Mr. Salonen’s new position in San Francisco.]

Since the late 1960s, when the fiery young Pierre Boulez said that the only solution to the entrenched conservatism of classical music was to blow up the opera houses and destroy all the art of the past, there have been calls for systemic change.

Yet Boulez mellowed over time, and became a revered figure at leading opera houses and orchestras, working within the system to improve it rather than exploding it. And Mr. Salonen, who came to attention as a flinty Finnish modernist composer, has taken a similar course. Yes, he wants to shake things up, but from the inside. In taking on another orchestra directorship, a decade after leaving a landmark tenure at the Los Angeles Philharmonic, he hopes to find the sweet spot between gutting the system and maintaining what works.

“The infrastructure of what we call classical music is going to evolve into something else,” Mr. Salonen said, though “we don’t quite know what it is.” But there is no reason to panic, he emphasized. “Obviously, it’s in no one’s interest to blow up the existing structure and start all over. It would be counterproductive.”

Mr. Salonen will arrive in San Francisco with something of a head start: Mr. Thomas has fostered a climate of experimentation. And Mr. Salonen certainly proved himself a model of fresh thinking during his 17-year tenure as music director of the Los Angeles Philharmonic. He has more recently refreshed the Philharmonia Orchestra as its principal conductor — including, in recent years, explorations of digital technology and virtual reality projects.

[Read our review of Mr. Salonen’s most recent concert in San Francisco.]

He comes at his new position, moreover, as a working composer. He suggested that, by “doing something as strange as writing new art music, you send out a very optimistic signal that I actually believe in this. And I believe in the longevity of the art form, and also believe there is a lot to be said still. When we talk about the masters, the underlying message is that the best has happened already. I don’t think so.”