The Beach Boys, the Beatles and Fleetwood Mac. Since initiating its "Covers: A Pop Concert" series three years ago, the male vocal ensemble Cantus has embraced a different classic rock album with each new season.

This year it was Joni Mitchell's turn, with the Canadian singer-songwriter's iconic "Blue" getting the close harmony treatment Saturday at the Cowles Center.

But "Blue" is far more intimate and introspective than "Pet Sounds," "Sgt. Pepper's" or "Rumours." Could Mitchell's 1971 release survive the transfer to an expanded format of eight voices plus keyboard, guitars and percussion?

In keynote songs such as "River," there was no doubt that it could. Baritone David Geist took the solo on Mitchell's devastating lyric of love and loss, accompanied only by the subdued harmonizing of his fellow singers. Geist's simple eloquence and mellifluous delivery were a high point, allowing the song's piercing combination of melodic beauty and raw emotion to hit home powerfully.

"Blue" is not all introspection, however, freeing up Cantus to play with stylistic changes in some of Mitchell's more up-tempo numbers. "My Old Man" acquired a distinctive doo-wop styling, while "Carey" was treated to an infectious salsa shuffle.

For a breezy "California," Cantus switched to an a cappella barbershop configuration. Keyboardist Lee Blaske even stirred a splash of Cajun into "This Flight Tonight," providing a spicy running commentary on accordion.

Inevitably, though, the biggest moments came in songs where Mitchell rips the veil to bare her most vulnerable feelings. The album's title song floated on a wave of unsettled harmonies, teased out in Cantus' arrangement from the sparse template of Mitchell's original piano and solo voice recording. In "A Case of You," Blaske's evocative church organ accompaniment — possibly referencing the "holy wine" in the lyrics — counterpointed bass Chris Foss' heartfelt solo.

And in the climactic "The Last Time I Saw Richard," the sober ruminations of Jeremy Boettcher's double bass underpinned a soaring performance by tenor Zachary Colby. Mitchell's vocal style is famously full of arabesques and twisting elaborations — it's virtually inimitable. But Colby's instinctively supple high-register singing caught its spirit evocatively, doing justice to a great song.

Framing the performance of "Blue" were half a dozen songs by other artists. Their mainly upbeat poppiness seemed to crash in from a different universe.

Cake's "Opera Singer" and Katy Perry's "Teenage Dream" gave the eight singers lavish opportunities to stretch their vocal chops and pull some dance shapes to the music, not always convincingly.

"Life on Mars" featured baritone Samuel Green's eerily plausible imitation of David Bowie's accent, with tingling block harmonies in the chorus.

But the disconnect between the 10 intimately revealing songs of "Blue" and the frivolity of the flanking program was obvious. Would it have been preferable to perform "Blue" in its entirety, either before or after intermission? The quality of Cantus' arrangements of Mitchell's songs, and the undiminished impact of their emotional honesty, suggest it might have been.

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