Every article about Musica Nuda talks about how vocalist Petra Magoni and double bassist Ferruccio Spinetti formed their unique duo in 2003. It was all because a guitarist Magoni was supposed to play a concert with cancelled at the last minute, so she asked Spinetti to fill in -- and they’ve been making music ever since.

This guitar player is never named, but he haunts every article like a ghost.

“His name is Paolo Fazzi. He’s still a guitarist. He has another job,” Magoni laughed. “No, we never played together -- never, ever. But he’s very funny because each time he reads the story in an interview he says, in a way, he’s happy because me and Ferruccio would have never played together otherwise.”

Fazzi’s loss was Spinetti’s eternal gain: Magoni has an amazing voice that fits in any setting, from jazz to French pop to disco -- all of which are in Musica Nuda’s vast repertoire. The duo has released 11 wide-ranging albums, including 2017’s Leggera, but on stage is where Musica Nuda shows its chops and charm. (See the Tuscany, Italy-based group at Kerrytown Concert House on April 29.)

Magoni is a dynamic live performer and her chemistry with Spinetti is mesmerizing -- and often hilarious. It’s as if Lucille Ball and Desi Arnaz became virtuoso musicians.

“The humor side, it’s something in me and Ferruccio,” Magoni said. “We are like that in life. I believe that there’s a moment to be fun, a moment to dance, a moment to scream, a moment to cry. I think a concert is like living one life in one night; we try to put all the shapes of music in one concert.”

Those wild mood swings are evident in Musica Nuda’s overall repertoire, which includes many originals alongside classics from all genres. There’s no single way the duo picks the songs it will record or play in concert; it's often as spontaneous as their shows.

“For example, we might listen to the radio while going to the concert and we say, ‘Oh, we can play this song tonight.’ There’s no rules,” Magoni said. “In fact, being just a double bass and voice is not a cage; it’s a big freedom because we can chose from every repertoire without losing our identity. So, even if we play Monteverdi or if we play The Beatles or a jazz standard, our sound is so unique that there’s no more repertoire -- each song is Musica Nuda.”

Sheila Jordan is one of the pioneers of singing with only a bass as accompaniment, and she was blown away by Magoni and Spinetti's ability to build on what she started and stamp their sound on any song they play.

“Many years ago, I had a class with Shelia Jordan,” Magoni said. “A couple of years ago, I was playing in New York and I invited her to our concert. It was a very beautiful moment because at the end she said to me she was very proud because we were going somewhere else [with the music] but she recognized her ideas [in the performance]. She said to me a very beautiful thing: ‘If I had your voice, I could speak to everyone.’ For me, it was a very, very emotional moment to have her in the audience and to have these words said by her.”

Musica Nuda hasn't recorded with Jordan, but the duo has collaborated with other musicians throughout its career, including the great jazz pianist Stefano Bollani (Magoni’s ex-husband). But two is the magic number.

“We love to collaborate because we believe we always learn something from other people -- musicians or even not musicians,” Magoni said. “But when we play with someone else and then we go back to playing together we say, ‘Oh, this is so much easier for us.’ We found each other in a musical way that is very, very special.”

Sorry, Ghost Guitarist.

Christopher Porter is a library technician and editor of Pulp.

Musica Nuda plays Kerrytown Concert House, 415 North Fourth Ave., on Saturday, April 29, at 8 pm. Tickets are $5-$30.