Back in 1985, Mission of Burma released a posthumous live album, The Horrible Truth About Burma, recorded on their final tour: a crop of songs they'd never gotten to record for real. The horrible truth was that they'd had to stop being a band before the world was ready for them. The Boston-based quartet had three kick-ass songwriters, avant-gardist aesthetics, wildly distinctive wall-of-sound playing (enhanced by offstage member Martin Swope's tape manipulations), and punk-rock overdrive energy; between 1979 and 1983, they played scorched-earth shows across the country, and made a dense, astonishing studio album, Vs., along with a pile of smaller records and demos. But guitarist Roger Miller's tinnitus forced them to split up.

Over the next two decades, Burma quietly became a post-punk totem: a band and a Pearl Jam album were named after Vs., R.E.M. and Moby covered their songs, compilation after compilation of their recordings was released. Meanwhile, the band remained silent. Miller and drummer Peter Prescott went on to other bands; bassist Clint Conley more or less gave up music to become a TV producer until he formed Consonant a few years ago.

And then, two years ago, they started playing as Mission of Burma again (with Bob Weston replacing Swope)--infrequently, for no other reason than that they felt like it, and with the understanding that they'd continue strictly at their whim.

"The chemistry was automatic, so that was no problem," Conley says. "Physically, it was a little bit of a challenge, especially for Peter, who hadn't played drums in many years. We rehearsed a lot, and it just fell right back into the channel."

All of a sudden, Burma was playing to audiences 10 times the size of the ones they'd left behind 19 years before. Conley says they were "flummoxed and flabbergasted" at how excited people were to see them: "To have been active musically in the '70s, and to think that anyone would care now--back then, the idea of listening to something 25 years old was unthinkable. Somehow, we've hit the postmodern time warp where everything splatters up against a brick wall."

The first big surprise was that they sounded great: even more muscular and limber than they had the first time around. (Miller is being very careful with his hearing--wearing shooting-range headphones, playing behind his amp, keeping a Plexiglas screen between himself and the drums--but he remains a ferociously inventive, brutally loud guitar player.) The second was that Burma's new songs were really good, too, and more and more of them kept appearing at their every-three-months-or-so gigs. Eventually, those songs turned into an actual new album, ONoffON. Conley calls it "our second album," and that's what it sounds like--not a reunion record, but a worthy follow-up that just took a while. (Three of its songs, actually, were kicking around Burma set lists circa 1982.)

The highlight of the record is Conley's "What We Really Were," adapted from a poem by artist Holly Anderson (a longtime Burma associate, whose words he's also used for "Mica" on Vs., as well as a bunch of Consonant songs). Conley calls it "a remembrance of a Greek Isle romance," but as a metaphor, Anderson's text is about the band addressing its own past from a distance to where the members see it clearly: "nothing that perfect or simple ever lasts for long."

Burma's still "keeping the horizons pretty short," as Conley puts it: they've got families and jobs (Miller's other gig is playing live soundtracks for silent films with the Alloy Orchestra); nobody's assuming that this reunion is permanent.

"Basically, we build things around our convenience and pleasure," Conley says. "That's one of the benefits of not being a professional rock band."

Even so, the band has been playing a bit more than it ordinarily would to promote the album--13 times in four months, including Burma's first-ever Portland appearance this week.

At a show in Philadelphia a few weeks ago, the Mission men opened with "Mica," then blasted into the first three songs from ONoffON. Over the course of two sets, they played as many new songs as old, and encored with the Wipers' "Youth of America"--a song younger than Burma itself is. They looked like they couldn't have been happier.

"Putting out the CD has upped the ante, for sure," Conley says. "What's kept us going is sheer pleasure--it'd be hard to overstate how intensely pleasurable it's been, tapping back into that music. But it's kind of tiptoeing across a minefield, hoping we don't step on something that blows us up."

Mission of Burma plays with Kinski on Sunday, June 6, at the Crystal Ballroom, 1332 W Burnside St., 225-0047. 9 pm. $15 advance, $17 door. All ages.