As does any group that comes from a collaboration of two exes - singer-guitarist Joseph Costa and singer-keyboardist Lindsay Anderson - who spent 7 years together and broke up before they'd even made a record. That Lindsay and Joe have recorded a trio of albums since then only confirms that the energy at the core of the L'altra sound - a moody mix of baroque balladry decorated with ambient electronics, simultaneously soothing and unnerving - is hardly commonplace. If we were allowed a sneak peak behind the curtain, the possible sociological studies and soap opera plot-twists could be endless. Except, it doesn't take much to play the voyeur on Joe and Lindsay's conversations - their continuous exchange is the beat of L'altra's heart. And if the group's debut, Music of a Sinking Occasion (2000) was the frictitious sound of two lovers disintegrating, and its unlikely follow-up, In the Afternoon (2002) was a restless exercise at pulling apart and learning how to live that way, then the new Different Days (2005) is the fruit of a socially unfathomable labor - the work of mates who never stopped weaving their musical minds (and singing voices) around each other, succeeding in their collaboration in a way their union could not.

"Our music is our baggage," says Costa. And what a very lovely set they have.

Lindsay Anderson and Joseph Costa's private alliance began long before their band leading came into question. The two met at a college in Cleveland in 1992: Lindsay was a poetry-writing melancholic from outside Toledo, who'd been a piano-playing prodigy at age 8, singing in church behind her drummer father and pianist mother. By college, her head was in the clouds of British Romantics like Keats, Byron, Shelley and Charlotte Smith. Joe had grown-up as a pop culture kid in Pittsburgh, learning to plunk out Tears for Fears songs on his first electric at age 14, leading to teenage garage-rock kicks throughout high school. By college, his pupils were dilated with the shoe-gazing stares of a different set of British Romantics, like My Bloody Valentine and the 4AD set. The focus of their aesthetic affection being roughly the same (only a century's difference), Joe and Lindsay had as much in common as any two college kids looking to hook up.

The next few years saw both transfer to Boulder, Colorado, then move to Chicago. As Chicago was a toddling town of indie-rock dementia in the '90s, it was simple for Joe and Lindsay to find musicians with whom to share their vision. Later, L'altra was formed with drummer Eben English and bassist Ken Dyber, who ran the Aesthetics label which put out their first records. Their secret ingredient arrived in the form of an old Wurlitzer that Joe had found lying in the garbage on one of his periodic visits to Pittsburgh. Lindsay took to it right away. "It seemed like an ancient instrument," she says. "It was the student model, this pretty beige color and the sound of it was of sadness. Take the Wurlitzer above the Rhodes or a piano, and it sounds really sweet and sad."

L'altra took on additional intensity when Lindsay and Joe separated during the weeklong recording of Music of a Sinking Occasion in 2000. By contrast, 2002's In the Afternoon featured a pair of exes learning the sweet hereafter, but a band in which "too many chefs were spoiling the soup," says Joe. "Though Lindsay and I wrote the songs, L'altra was definitely a democracy, we'd fight about what should happen to the songs. We both felt that the second record was meandering and over-arranged, that there were too many voices involved. So we got rid of everybody."

Says Lindsay, "It seemed silly trying to keep a band together - it was not about that."

Joe was living and working in Santiago, Chile in 2003 when he and Lindsay began discussing a new L'altra album, and began writing songs -- for the first time separately, which is where and when the strength of their collaboration became most apparent. "It was like we were present in each other's minds when we wrote these songs," says Lindsay. "Playing together for so long, I know what he's going to hate and like when I write. I know that he does that too, writing on the guitar, thinking of what I'll do on the Wurlitzer."

When they got together in Chicago to record some demos, they took to each other's compositions, bringing a little bit of themselves to the other's work, making the planned course obvious. Though, with the demise L'altra's democratic make-up, a new member of what Joe calls "me and Lindsay and a collective" came to the fore to help produce Different Days: Telefon Tel Aviv's multi-instrumentalist Joshua Eustis. Besides laying down everything from bass parts to Mellotron effects, Eustis played a psychological part in emboldening Joe and Lindsay's tag-team.

"He was a great intermediary between Lindsay and I, calming us down in the studio. He pushed us to do things that we would have been afraid to, he encouraged us to go over the cliff."

This may be why Different Days is a stormy and fierce animal in comparison to previous records, bringing the heady waves that always lurked beneath L'altra's calm exterior crashing to the surface. Listen to "It Follows Me Around," the way Costa's guitar laps Eben English's tight kit, while Joe and Lindsay's harmonies ride the skipping cello; or to the feedback and the dub echoes that make gray fuzzies around the lonesome guitar on "Bring on Happiness." They, like many of the album's songs, redefine L'altra's idea of space as something both greater than you can ever imagine, and more intimate than you can stand.

And at its heart, Different Days is a conversation between two people trying to make sense of this space: "On almost every song, when I sing a part," says Joe, "she sings back at me. We may no longer necessarily be the people we are in our songs, but music is a way that Lindsay and I have come to communicate. Now we get to pretend."

Looks like Lindsay and Joe have become the "other" after which they named the band.