It’s important to know what to expect from a show when the marquee lists four talents as formidable as Emmylou Harris, Shawn Colvin, Patty Griffin and Buddy Miller – and particularly when the ticket prices are jacked up as high as they have been for this year’s “Three Girls and Their Buddy” extravaganza. Surprisingly, the tour has left a trail of mediocre responses from critics and bloggers griping about the limited song selection for each artist, the lack of “greatest hits” performances or evidence of much rehearsal, the ratio of between-song patter to actual tunes sung, and the short running time (just under two hours).

The problem, most likely, is one of scale. The idea of the tour is to replicate the famed songwriters’ circles at the Bluebird Café in Nashville, or the “In Their Own Words” series that Vin Scelsa used to host at the dearly departed Bottom Line in New York. Those gigs, however, traditionally are/were performed for audiences of just a few hundred, all of whom paid a modest price for their tickets and most of whom were well-versed in the concept of “a bunch of songwriters sittin’ around singin’,” as the Bottom Line concerts were subtitled. But last night L.A.’s legendary Greek Theatre packed in something more like 4,000 souls, the majority of whom had paid north of $50 for the privilege, and in the concession lines too many patrons were heard pronouncing their excitement at the chance to hear one star in particular. One guy in the smoothie line, asked by the clueless, Hawaiian-shirted mixologist who the night’s performers were, replied, “It’s a Shawn Colvin show.”

No, it wasn’t. The real fun of a songwriters’ circle is its aura of surprise – the possibility that somebody will play a new song you haven’t heard before, or drag a musty old tune out of her back catalog … or that you’ll come away from the show a huge fan of the one person whose music you were least familiar with when you came in. All those charms are abundant on this tour, even if they’re low-key ones, and the experience is a rich and satisfying one – unless you come to hear “Sunny Came Home” or “From Boulder to Birmingham,” in which case you’re out of luck.

The women led off the show with a sweetly harmonized version of Phil Spector’s “To Know Him Is To Love Him,” which was on the Harris/Parton/Ronstadt Trio album nearly 30 years ago – and which the Three Girls had begun dedicating to Buddy after a heart attack and triple-bypass surgery forced him off the tour back in February. Harris followed with a rendition of “Red Dirt Girl,” commencing five rounds of turn-taking during which the singers accompanied each other vocally and with guitars, tambourines and shakers. (A roadie at stage left even marked each round of songs with a numbered sign, like at a boxing match.)

In this match, Miller was the clear underdog – by far the least-known quantity onstage, though he’s a ubiquitous presence in Americana circles. “Sorry,” he intoned when his first turn came. “I know I’m not what you expected … but my songs are short, and Buddy Hackett wasn’t available … or Buddy Emmons … or Buddy Guy.” With that, though, he launched into the knife-like guitar runs and rollicking vocals of “Gasoline and Matches,” from his new album with wife Julie, and the audience was his. Indeed, Miller’s songs were consistently revelatory – a word I mean in two ways, since he sang a trio of gospel numbers from his Universal House of Prayer album, which I’m guessing a couple hundred concertgoers probably fished off Amazon and iTunes this morning. “I’m the luckiest guy in the world,” he said later, and it was easy to take him at his word – not only because of the company he’s keeping, but because of the exposure his presence in that company is bringing to his own music.

Miller is currently producing a gospel-tinged album for Griffin that will be released over the winter – a “lapsed-Catholic gospel album,” as she identified it repeatedly – and on this tour the two of them are clearly in cahoots, enabling Griffin to emerge as the evening’s strongest (female) voice. Her soprano pierced the night sky on her own gospel numbers – the first a cover of Blind Willy Johnson’s “If I Had My Way, I’d Burn This Building Down,” the second a self-penned number called “Coming Home to Me.” She also performed the entirety of what she called her “love songs” series – which she introduced by saying, “I’m 45, and I’ve written exactly two love songs in my life.” The first was “Heavenly Day,” from her Children Running Through album, which she said is becoming a popular wedding song “even though I wrote it for my dog”; the second was the hysterical “Our Love is a Dud.”

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Harris got with the program by singing a couple spirituals of her own; indeed, at one point Miller, she and Griffin sang three of them in a row … which the thoroughly secular Colvin followed, irony perhaps or perhaps not intended, with her “folk-hip-hop” version of Gnarls Barkley’s “Crazy.” Colvin was rather subdued throughout, despite the fact that her new Live album had been released the day before. She led off with “Trouble,” from A Few Small Repairs, but then sang only one more original tune the rest of the night (“Summer Dress”) in addition to Robbie Robertson’s “Twilight” and the Beatles’ “I’ll Be Back,” on which she led a particularly exquisite three-part harmony.

The evening concluded with three group sings, capped by a gorgeous performance of what Harris called their “benediction” – Griffin’s “Mary.” It was a fitting conclusion, since Griffin had dominated the proceedings both thematically and with her generous wit. All in all, the evening could have used a bit of Scelsa’s (or perhaps Jules Shear’s) gift for eliciting interesting stories from his “In Their Own Words” participants, but the music – though it might not have included the best-known songs from any of the four artists – and the communal vibe were all an audience could (or at least should) ask for on an early-summer evening outdoors at the Greek.