I admit it: I'm an Indigo Girls fan.

And what of it? So what if I'm moved by their music or touched by the homey eloquence of their lyrics? I have no apologies for singing along with the crowd huddled at the stage during Tuesday's show at Kingsbury Hall. And I'm only slightly embarrassed that, earlier in the day, I waited 45 minutes for an autograph during their appearance at a local record store.Nope. I'm an unabashed, unrepentant enthusiast for the music of Amy Ray and Emily Saliers, a k a Indigo Girls, whose knockout performance Tuesday at Kingsbury Hall will be talked about for years to come.

That's not to say the Indigos had an altogether go of it. Salt Lake audiences can be tough to crack, and the Indigos realized they had their work cut out for them when, after four or five songs, virtually everyone in the house was still seated, content to enjoy the show without kicking up their heels.

At one point, Saliers, seeming genuinely bewildered at the restrained response, asked, "Is it a rule that people can't dance in Salt Lake City?"

Part of the problem may have been that the first hour of the show was devoted almost entirely to selections from their new album

"Nomads*Indians*Saints," and the audience, although appreciative, may not have been familiar enough with the music to give the expected response.

But the tide turned when Saliers and Ray struck the opening chords to "Closer To Fine," their biggest hit from a year ago. At that point, spectators at last became participants as fans abruptly swelling forward and quickly overwhelmed the small contingent of beefcake surrounding the stage.

From there, it was all downhill as the Indigos moved rapid fire through material culled largely from their first and thus-far most successful LP titled simply "Indigo Girls." Of those, "Closer To Fine" seemed to inspire the most enthusiasm, but my personal favorites were "Kid Fears," "Prince of Darkness" and the soothing, mesmerizing "Love's Recovery."

What's their secret? Hard to say. There's nothing terribly innovative about their all-acoustic format (although it is striking in the age of techno-pop to see two figures alone on stage with only acoustic guitar and microphone). Their melodies are simple and straightforward, and their lyrics, although interesting, aren't exactly profound.

But there is something about the Indigos' treatment of songs that somehow metamorphoses otherwise ordinary pop tunes into soulful, surprisingly moving pieces. Their voices - especially Ray's - are steeped in feeling, and the emotion somehow seems genuine, not just stirred up for the audience's benefit. There is conviction here, and one gets the feeling that Saliers and Ray are sharing insights gained through sometimes painful introspection and personal experience.

Take, for example, Saliers' "The Girl With the Weight of the World in Her Hands," a song in which she proposes greater understanding for those social misfits who seem to be always on the outside looking in.

Her point is succinct and vivid: "She's called to our attention/But we do not call her name."

And while their voices are both powerful, they are very different. Ray's vocals almost drip with emotion, while Saliers shows more control, careening effortlessly up and down the musical scale. When Ray wails almost gutturally on songs like "Prince of Darkness," Saliers answers with a soft, plaintive counterpoint that seems somehow to keep the song from sinking into schmaltz.

Part of what makes Indigo Girls so much fun in concert is just how much they seem to enjoy their work and each other. The two began their working relationship in high school, and both profess to have a genuine friendship that goes beyond their musical collaboration.

It's that chemistry that propelled them to stardom and it's what may well sustain them where many other bands have split under internal tensions.