PARIS — On a rain-soaked afternoon in Paris’s edgy 11th Arrondissement, Antoine Naso squeezed down a winding staircase in his tiny office and walked toward a coterie of young men awaiting their chance to audition in an airless basement.

Mr. Naso has a somewhat unusual job: He is an artistic director for the Paris Métro. But it is one that he takes just as seriously as his counterparts at the opera.

“Why are you here?” he asked, as they stood at attention under a glare of spotlights.

Thibault Couillard, a poet and musician, blinked nervously and cleared his throat. “We’d like to get this gig,” he replied, reaching for a microphone while his confreres unzipped damp bags and pulled out two guitars, a jury-rigged pedal drum and a melodica. “If we could play before huge crowds, that would be magical.”

It was nearly the 200th performance that Mr. Naso had heard in 10 days. But by the time Mr. Couillard’s band, the Danny Buckton Trio, finished a set of Serge Gainsbourg-style numbers, Mr. Naso was convinced. The group would get one of only 300 coveted permits that allow artists to perform almost anywhere they want, any time they want, in the subterranean theater that is the Métro.