When you've been working on a single project for over 16 years, the logic goes that few things might surprise you when you're close to the finish line. But according to Tony Di Blasi, one half of Australian sample-pop duo the Avalanches, turning in the final product was more shock than relief.

"You'd think it would be an exciting moment, but instead it was this really strange feeling," Di Blasi says on the phone from Sydney, where the Avalanches have just curated their own festival outside the city's famous Opera House. "It was this huge part of my life that I was so absorbed in for years—decades—and then all of a sudden it was gone and something was missing. It felt very bittersweet."

The feeling Di Blasi is describing—an eternal longing for something just off in the distance—is at the heart of the Avalanches' landmark 2000 debut album, Since I Left You, a touchstone of the crate-digging era most figured would stand as the band's lone definitive statement. Assembled from over 3,500 individual samples, it's a party album that's actually best for the afterparty, a pancultural mixtape curated equally from obscure golf instructional records and Madonna hits. It brought the group, which now consists of just Di Blasi and main producer Robbie Chater, waves of critical success, a growing cult of hardcore fans and crazy expectations for a follow-up that was teased and teased throughout the aughts until no one, band included, knew if it would ever see the light of day.

Released last July, the second Avalanches record, Wildflower, contains no hints of the struggle and self-doubt that clouded its fraught creation. Jubilant, wondrous and almost childlike in its sense of discovery, it takes the group's groundbreaking pastiche of samples and found sounds to the major leagues, with live instrumentation and contributions from an eclectic group of guests, including rappers Danny Brown, Biz Markie and Camp Lo, Jonathan Donahue of Mercury Rev, and David Berman of Silver Jews. (Berman also ended a long artistic silence by contributing a heartbreaking spoken word track that became the album's final track "Saturday Night Inside Out.") The album's mix of hip-hop, disco, wayward folk and psych rock somehow holds together, though piecing together so many disparate threads played into its long delay.

"There are definitely songs that came together every year during the whole period," Di Blasi says. "The last couple of years was mainly working on ways to put it all together, which was quite hard to do. Since I Left You is a bit more similar from song to song, and on this one the individual tracks have stronger personalities."

Di Blasi describes the album's narrative as something of a drug-addled road trip, with the action moving from dense sprawl to a more pastoral countryside. "The start of the record feels like kids in the city hanging out, it's a bit fun and crazy, and around 'If I Was a Folkstar' you get out to the open plains," he says. "You go from hustle and bustle to peace and nature."

Though the Avalanches credibly make what could be called "dance music," their closest references are more in line with the warm summer nostalgia of the Beach Boys or other late '60s psychedelic records. There's a pastoral, longing quality to everything they've produced. Songs like "Since I Left You" and "Subways" sound timeless because they're composed of so many fragments of the past. If Since I Left You was hippie music for the Napster era, then Wildflower is a reflection of our current times—a well-curated Spotify playlist for your backyard barbeque or cross-country adventure. It's the sound of two humans you thought you'd never hear from again, jumping back into the game after years of isolation.

"We cut ourselves off from the world during the making of Wildflower—we didn't really go out much, which is terrible," Di Blasi says, laughing. "It's been amazing playing shows and being more socially active again. We have to make music. It brings so much joy to people and it brings so much joy to us. We don't want to go away for another 16 years."

SEE IT: The Avalanches play Crystal Ballroom, 1332 W Burnside St., on Wednesday, July 12. 8:30 pm. $26 advance, $30 day of show. All ages.