NEW YORK, NY.- In late January 2016, Akinobu Oda — a Japanese restaurateur and concert promoter — taped a red-and-black handbill demanding “Don’t disturb!!!” to the window of his vegan dive in Tokyo. The reason? The American art-rock band Gastr del Sol was dining inside.

It had been 18 years since the duo split. During the late 1990s, David Grubbs and Jim O’Rourke enjoyed an intense and prolific partnership, working together in multiple groups and running the audacious label Dexter’s Cigar. But they hadn’t seen each other since 2002, communicating only through sporadic emails. In Tokyo, they were finally face to face.

“Our breakup was hard, because what had started as a very easy collaboration wasn’t easy anymore,” Grubbs, 56, said during a recent video interview from his Brooklyn apartment, where he was surrounded on one side by rows of records and on the other by decorative plates and vases. “I wasn’t sure how it would be, but we were there for hours after the restaurant closed.”

That summit became the first move in a long path to “We Have Dozens of Titles,” a three-LP box set due Friday that includes the first previously unheard music from Gastr del Sol in a quarter-century. It is the end of the vault, and there will be no reunion shows or sessions.

Still, with its out-of-print obscurities and several unreleased live recordings, the compilation reaffirms just how unusual the music that Grubbs and O’Rourke made during their five-year run still is. Though their music began with two carefully intertwined acoustic guitars, it stretched to encompass orchestral fantasias, electronic abstraction and collage sensibilities imported from the avant-garde. Grubbs’ image-rich writing felt poetic and detached. In an era of plangent indie rock, they were the studied, intricate eccentrics.

“Their last record, ‘Camoufleur,’ was like a report on European music and American primitivism, perfectly warped into this pop record,” said songwriter Ryley Walker, who was a teenager in Illinois when he discovered the 1998 album in the dollar bin of the shop Reckless Records. It opened his ears to endless possibilities. “They said, ‘How can we take something so weird and make it pleasant?’”

As a music student at DePaul University, O’Rourke — a Chicago native raised by blue-collar Irish immigrants — had been a near-daily presence at that same store. He despised school, resenting how out of touch it was with frontiers of modern composition and electronic music. So at Reckless, he ordered imports from those fringes. And each summer, when school let out, he would fly to Japan with armloads of albums that had never been released there (including a Kiss compilation, 25 cents per copy in Chicago) and offload them at a premium. He’d continue to Germany with Japanese titles and repeat.

“I had this Bermuda Triangle of record selling to sustain my hobo lifestyle,” O’Rourke, 55, said in a video interview, laughing behind a cloud of cigarette smoke in his studio in Japan, where he’s lived since 2005. Power cords dangled from most surfaces, with a Serge modular synthesizer visible over his right shoulder. “But I was finding more people aware of things I cared about, people to work with.”

By 1993, Grubbs had met O’Rourke once before and considered him mysterious, lurking in the aisles of Reckless for 30 minutes before anyone noticed, or jetting overseas to work with older musicians. Though Grubbs was a classically trained pianist, he had been an enthusiastic Kentucky punk, putting out his first record with the Happy Cadavers in 1982, at age 14. His subsequent bands, Squirrel Bait and Bastro, found underground acclaim by warping atavistic rock.

In Chicago, where Grubbs had come to study English in graduate school, he began to contemplate quieter music, writing on unplugged electric guitars alongside Bundy Brown, his roommate and Bastro bandmate. Brown worked at Reckless, too, so he’d borrow records rooted in radical jazz and serial composition and bring them home. Meanwhile, Bastro drummer John McEntire was studying at Oberlin Conservatory and sharing his finds, like the abrasive composer Iannis Xenakis. (Brown and McEntire went on to join post-rock fusionists Tortoise.) So when Grubbs finally saw O’Rourke performing in a cramped den called Lower Links in 1993, his conception of music was rapidly expanding.

“I’m not sure I’d ever seen a solo improviser before,” Grubbs said. “And after this really austere set of spiky improvisations, he put Van Dyke Parks’ ‘Discover America’ on the sound system. That was the sense of range one hopes for in a collaborator.”

The pair became fast friends, geeking out over finds in the other’s collection. Grubbs introduced O’Rourke to theatrical singer Scott Walker and chaotic cuts of American hardcore. And he delighted in O’Rourke’s specific enthusiasms, or how he could cite what made a certain John Cage or Charles Ives recording the best. Grubbs had already finished “The Serpentine Similar,” his debut as Gastr del Sol with Brown and McEntire. O’Rourke, happy to be working at last with someone his age, penned his own parts for that material as new songs also emerged.

Bouncing between O’Rourke’s studio in his parents’ basement and Grubbs’ apartment in Hyde Park, they wrote their first album, “Crookt, Crackt, or Fly,” within months. “It was a piece-by-piece, album-by-album exploration,” Grubbs said. “Jim and I tried to amuse and amaze one another — and hopefully not repeat ourselves.”

In turn, Gastr del Sol directly widened the scope of indie rock, not only folding in jazz players and digital pioneers, but also repeatedly partnering with minimalist composer Tony Conrad. After helping name the Velvet Underground and working with La Monte Young, Conrad had mostly receded into academia and experimental films. (During the interview, O’Rourke sported the same Conrad T-shirt he wore for Gastr del Sol’s press photos 30 years earlier.) Conrad’s sessions with Gastr del Sol forged a renaissance that lasted until his 2016 death.

“Jim is a tremendous electroacoustic composer, and David is full of sophisticated nuance — impressionistic lyrics, undulating guitar work,” said Jeff Hunt, who linked them with Conrad and released many of their recordings together through his label, Table of the Elements. “They complemented each other like Japanese joinery — no glue, no fasteners, a perfect fit.”

In their fecund Chicago scene they became incredibly busy. O’Rourke played on or produced records by the likes of Smog and U.S. Maple while shaping his own gorgeous solo works, like “Bad Timing” from 1997. Grubbs remained in school, pursuing his doctorate in a start-and-stop process that lasted a decade. Both played in the Red Krayola, a long-running, ever-amorphous collective. Given other commitments, once-complementary roles calcified into strict divisions.

Seams started to show. Resentments grew. Deep fatigue set in. Days before Gastr del Sol began a tour in fall 1997, O’Rourke told Grubbs he was staying home to assemble “Camoufleur,” the first time he’d used the digital editing software Deck II. He’d spend 15 minutes waiting for his Macintosh to render mere seconds of audio.

When they finally finished the album, O’Rourke called to say he quit. Grubbs was less surprised than disappointed, since the glitchy symphonies, vertiginous waltzes and galloping instrumentals on “Camoufleur” suggested they weren’t finished. “That record was a flowering of what we’d done over five years,” Grubbs said, sighing.

But O’Rourke knew there were sounds and situations he craved beyond Gastr del Sol’s boundaries: “I didn’t like my life being constrained by one thing.”

Before their 2016 lunchtime rendezvous, Grubbs and O’Rourke apologized to each other via email. O’Rourke said he knew his approach had been manic and obsessive, with 14-hour workdays that allowed for little else. For his part, Grubbs wished he had been less serious and more generous, more open to understanding the viewpoint of his bandmate and best friend.

Still, as they were recently revisiting the music they’d made, something surprising happened, especially for O’Rourke, who eschews nostalgia: He noticed how interesting they’d been, how sophisticated the choices they’d made in their 20s remained. He recalled “Bells of St. Mary’s,” their contribution to a Japanese Christmas album where they were again the quiet outlier, electronic pulses and organ hums framing gentle piano.

“I only had a vague memory of it, but the pace is so good,” O’Rourke said in a subsequent group conversation, Grubbs grinning and nodding along. “There’s that one bass note that comes from the Farfisa at the end. Everything you’ve heard changes context with one note.”

This article originally appeared in The New York Times.