Some artists never quit. With more than 19 years in the music industry, nine albums of new material and countless live performances as evidence, it is unquestionable that Emily Saliers and Amy Ray of the Indigo Girls are two such artists.

Less than a year ago they played for crowds at Madison’s Orpheum Theatre. Last July they performed for energetic audiences at Milwaukee’s Summerfest. They will return to entertain eager Wisconsin fans March 28 at Overture Hall. If their past success serves as any indication, the Overture ticket outlet will likely experience lengthy lines come 11 a.m. this Saturday, when tickets for this show of the Perfect World Tour will be made available.

Promoting their newest album, the 2004 Sony Records release All That We Let In, the Indigo Girls prepare a bit of a departure from their characteristically acoustic-dominated sets with a full band.

The record still boasts of the melancholy lyrics that fans have come to know the duo for, often centered on the ups and downs of relationships. The standard harmonies, ringing from clear, Georgia-accented voices, return in the title track and “Free in You.” Likewise, the moments of fierce activism and social commentary appear in numbers such as “Cordova.”

On the other hand, there are a few surprising tunes that demonstrate the evolution their sound has endured over time.

The album contains numbers possessing a new kind of energy, an increased optimism in the lyrics and an amplified energy in the higher tempo beats. The Indigo Girls allow new influences to infiltrate, such as “Rise Up,” which displays piano stylistics reminiscent of Elton John. Similarly, audiences will hear an echo of ska backings with “Heartache for Everyone.”

The anticipation of experiencing the performance of such new songs helps the Indigo Girls fill up venues. With a powerful and devoted collection of audiences, Saliers and Ray find themselves able to experiment with changing genres. Fans constantly embrace the duo’s abilities however the sounds might come out and regardless of the manner in which they might experience them

Proof comes when the Indigo Girls carried on a scheduled performance in New York City’s Central Park in 2003 in the midst of a power outage. While some artists did not want to play, Saliers and Ray found themselves singing for crowds that encouraged the new songs just as much as the old.

Ask any Indigo Girls’ fan about his or her continued enthusiasm for the group and a common response will begin with the live show. For some devotees, the 30-dollar ticket to see the set for the third or fourth time during one tour is no more an inconvenience than numerous hours of driving time to reach a venue.

Knowing many travel to see them numerous times, Saliers and Ray found a way to keep their performance philosophy constant and still ensure each show proves a new and memorable experience.

From the March show, many can expect an evening of not only entertaining music, but also a demonstration of the close relationship between the twosome and their audiences. Sharing anecdotes, expressing concerns over the issues they sing about or explaining the foundations of particular lyrics and accompanying sounds, the Indigo Girls make attempts to create a show that is less about their performance on stage and more about their interaction with those in the auditorium.

This feeling of community is improved by the inevitable crowd participation in the sing-along. The classic standard “Galileo,” which has been making the play list for hundreds of shows since its 1992 debut on their album Rites of Passage, often consists more of the audience singing than the Indigo Girls themselves. Similarly, the night is not complete until “Closer to Fine” and “Power of Two” have echoed through a venue.

With such a vast collection of songs to choose from, mixing the beloved songs from years past with the most recent releases bound to become favorites, the set list is a veritable grab bag. Each performance from the Indigo Girls is unique unto itself, never to be exactly replicated, prompting many to already begin preparing their stakeouts for the opening of the box office this Saturday.