The last year has been a good one for old artists looking to make a comeback. A number of the acclaimed acts of yesteryear thought to have called it quits for good are embarking on reunion tours, more-than-a-reunion tours and new music from the studio, perhaps taking advantage of the relative open range of the industry in a digital world. In this decade alone, we’ve seen the returns of My Bloody Valentine, The Jesus & Mary Chain, The Avalanches and A Tribe Called Quest, to name a small few.

This May, two such bands converged on Atlanta in the midst of the fifth annual Shaky Knees Fest, which brought a stacked lineup of indie and alternative bands to Centennial Olympic Park from May 12 to 14. England’s Slowdive, though not technically part of the lineup, kicked off the weekend Thursday night with a show at Atlanta’s Variety Playhouse, less than a week after releasing a self-titled album, their first in 22 years. The following night, James Murphy and LCD Soundsystem brought their comeback tour to Shaky Knees on the heels of two new singles, their first output since a much-ballyhooed breakup in 2011 (followed by an equally melodramatic return at last year’s Coachella).

Even with up-and-comers like Pinegrove and Twin Peaks giving scrappy energy to the festival, it was the returning veterans who stole the show at Shaky Knees.

Formed in Reading in 1989, Slowdive arose from the “shoegaze” movement that arose in Britain in the late 1980s and early 1990s, so named for the innumerable effects pedals that lined the stage of these artists’ live shows. Maligned by contemporary critics for its ethereal, dream-like quality, shoegaze music was pushed aside by the mainstream in favor of its tougher cousin, grunge rock. But among fans of underground music, the genre has aged well, with albums like My Bloody Valentine’s “Loveless” and Slowdive’s “Souvlaki” becoming hallmarks of the era.

The secret to bands like Slowdive is that, underneath the wash of chorus and delay effects, the music boils down to incredibly simple pop arrangements—often played at a pace that tests the patience of any casual listener. It’s the kind of music that could fail to make an impression if played merely in the periphery. But the essence of shoegaze music is that, for all its harmlessness, it’s deceptively loud music: it’s designed to be turned up to the max (preferably through headphones, preferably alone), mimicking the intensity of an introspective mind. It is no wonder that, of all the subsets of alternative music, none is more emblematic of the lost-in-thought loner than shoegaze.

Slowdive’s show at the Variety Playhouse turned this raw power outward, putting together a wholly immersive live experience. Though their set rarely exceeded a plodding mid-tempo, the soaring guitar riffs combined with the vocal interplay between Rachel Goswell and Neil Halstead took on a new dimension in the packed venue than they ever could at home. It certainly didn’t hurt that the established act was backed up by a spectacle of strobe lights and surrealistic visuals, achieving a rare full-body experience for the concertgoers (many of whom sported their own noisy artists of choice—a dude in a “Psychocandy” tee was a common sight).

A brief, human moment occurred midway through Slowdive’s set, when Goswell came in with backup vocals a couple measures too soon. Far from being embarrassed (though Halstead seemed less enthused by the error), Goswell let out an audible laugh on-stage, continuing to smile even when she had recovered her part at the correct time. In that instance it was clear that, unlike the sometimes acrimonious or depressing reunions of aging rock bands, the members of Slowdive, now well into their forties, were enjoying themselves as much as ever.

On Friday, LCD Soundsystem rounded out a first day at Shaky Knees that included a formidable triple-header from Pinegrove, Twin Peaks and Preoccupations (formerly known as Viet Cong) at the Ponce de Leon Stage as well as appearances from North Carolina natives Rainbow Kitten Surprise and indie rock legends Pixies. A collective of musicians helmed by frontman James Murphy, LCD Soundsystem rose to prominence in the early 2000s with its synthesis of electronic dance music with the trends of modern indie music. In Atlanta, their set was preceded by a rowdy show from Cage the Elephant, one that seemed designed to hit the pleasure points of Shaky Knees’ target demographic. One got the impression that, after the crowd-surfing, Jagger-esque machismo of Cage the Elephant’s Matt Shultz, the long-form electronic grooves of LCD Soundsystem may have lost the interest of more than a few in the audience—and, indeed, the crowd thinned out enough between the two sets that it was possible, though difficult, to weave a way toward the front.

Amid an enviable array of analog synthesizers and at least three drum kits, Murphy stood front and center, sometimes clutching his trademark vintage cardioid, sometimes pacing the stage and fiddling playfully with his bandmates’ equipment. For the marathon two-hour set, Murphy and Co. toured their own back catalog with early hits like “Daft Punk Is Playing at My House” and “Someone Great,” before bringing out week-old singles, “call the police” and “american dream”—their first new material since the 2010 album “This Is Happening.”

The music was buoyed by Murphy’s stage presence, his typical bedhead and five-o’clock shadow a hint of his wacky, sarcastic persona. He greeted the audience with an enthusiastic “Hi, everybody!” at least five times, kicking off each song by introducing his bandmates (“This is Nancy. Hi, Nancy!”). He seemed to recognize the post-Coachella dynamic of the festival’s constituents, poking fun at the youthful demographic.

“If you don’t know us, and someone asks how the show was, just say, ‘They were old and they played a bunch of old stuff,’” Murphy joked.

A giant digital display emblazoned with the festival’s name accompanied by various images of Instagram-worthy nature landscapes provoked jabs from Murphy, who interrupted a rendition of “New York, I Love You but You’re Bringing Me Down” with a running commentary on the display’s incongruity with its home in downtown Atlanta: “Why mountains?...Why the ocean?”

Noticeably absent from the set, though, was LCD Soundsystem’s breakthrough single “Losing My Edge,” which finds Murphy lamenting his loss of cool credibility to the kids “coming up from behind.” Perhaps its omission is an indication that his band has finally come to terms with its age, an acknowledgement that would fit well with the band’s recent return. For bands like Slowdive and LCD Soundsystem, their live comebacks and their new studio output shows a genuine comfort and enjoyment in making music that transcends any eras or trends. They don’t have anything to prove, which makes their renewed presence that much more enjoyable—and they know this because, to paraphrase Murphy in “Losing My Edge,” they were there.