There was a time, not long ago, when 29-year-old singer Samuel Green had zero clue about Joni Mitchell.

"I was very heavily influenced by jazz music," he said. "And everybody was saying, 'Oh, you've got to listen to Joni.' And I said, 'Who's that?' "

Green was an undergrad at the University of Missouri-Kansas City when some fellow students turned him on to the Canadian singer-songwriter's collaborations with jazz bassist Jaco Pastorius.

Almost a decade later, Green is a bass with Twin Cities-based Cantus. The eight-man vocal group mainly performs classical music. Once a year, though, Cantus turns its attention to a well-known rock album, performed in its entirety with new bespoke arrangements especially for eight voices. And this year's installment features a close harmony treatment of Mitchell's iconic 1971 album "Blue."

It's a surprising choice for an all-male ensemble whose previous selections include the Beach Boys' "Pet Sounds," the Beatles' "Sgt. Pepper's Lonely Hearts Club Band" and Fleetwood Mac's "Rumours."

So what drew this group of millennial male singers to an album written nearly 50 years ago by a pioneering articulator of women's thoughts and emotions?

The album's emotional honesty, with its frank descriptions of unraveling relationships, speaks powerfully to a younger generation of listeners, Green said.

"Joni's content is super-personal and vulnerable. The rhythms of her lyrics are so speech-like it sounds like she's having a conversation with the listener."

Perhaps "Blue" has special resonance "now that our society is dealing with a lot of issues relating to masculinity," added Cantus bass Chris Foss. The album's intelligent, emotionally articulate songs "allow men to share and talk about their feelings, and not in some hyper-romanticized, hugging-it-out-in-a-drum-circle type of way."

In fact, Foss, 35, ranks "Blue" with the great classical song cycles such as Schumann's "Dichterliebe" or Schubert's "Die Winterreise," both anguished studies of disappointed love.

"I think that 'Blue' is one of the greatest song cycles that's ever been written," he said.

What would Joni do?

"Blue" feels all the more confessional thanks to the way Mitchell recorded the album, with little more than a guitar or piano supporting her uniquely plangent vocals.

Adapting that spare, uncluttered soundscape for eight male voices proved a meticulous process. To get started, each singer spent the past year developing one or two songs. Studying each recording, they found, eventually yielded the song's inner secrets, suggesting ways it might fit with the Cantus specialty for layered harmonies.

"We were working on 'River,' " said tenor Jacob Christopher, 35. "And I remember just singing it in my apartment and literally not being able to get through the lyrics. There's so much emotion in them and I'm choking. You kind of get that out at home so you don't do it on stage."

Further alterations happened during rehearsals this month. "There are times when you can kind of hear that your idea for a song is not going well, and you have to make adjustments," he said.

Foss often doubles on acoustic guitar for Cantus performances. This time he'll team up with a small ensemble featuring bass, drums and piano. Yes, he's up for the challenge of capturing Mitchell's famously unorthodox guitar tunings, which shift from song to song..

"Once you get past the tunings, it's actually easier for the fingers to play certain chords and get certain sounds," he said. "That's why Joni did it."

'A true masterpiece'

After immersing themselves in "Blue" for the past year, all three Cantus singers eventually settled on a favorite song.

For Green it's the title track. "Because life happens," he said.

Christopher favors "Little Green." "I'm a sucker for a devastating, heartbreaking lyric," he said. "And it's just beautiful."

"The Last Time I Saw Richard" is Foss' pick. "It provides a kind of summation and puts everything into context."

Working on "Blue" certainly sharpened their appreciation for the album, with its devastating insights on feminine psychology. But the Cantus singers insist they didn't seek out "Blue" simply because they were due to sing songs by a woman.

"We chose it because Joni Mitchell is one of the greatest songwriters who's ever lived," Foss said. "And 'Blue' is a monument of her art, a true masterpiece of any type of music."

Joni Mitchell's 'Blue'

What: A covers concert by Cantus.

When: 7:30 p.m. Fri.-Sat., 3 p.m. next Sun. Ends June 8.

Where: Cowles Center, 528 Hennepin Av. S., Mpls.

Tickets: $27-$37; 612-435-0055, cantussings.org.

Terry Blain is a freelance classical music critic for the Star Tribune. Reach him at artsblain@gmail.com.