They've toured and recorded together, in one incarnation or another, for more than half a century, racking up dozens of hit albums and singles along the way. They've been members of the Rock and Roll Hall of Fame since 1992, and they've continued to release new music in the 21st century even as samples from their remarkable run of classic hits have surfaced in countless hip-hop tracks. The Isley Brothers are part of the bedrock of modern American music, and it would be impossible to overstate their influence -- yet they've never been afforded the comprehensive reissue treatment.

Until now, that is. With the release of The RCA Victor & T-Neck Album Masters (1959-1983), a beautifully compiled 23-disc box that gathers 21 of the group's earliest bestselling LPs while tacking on a healthy array of previously unreleased bonus material -- including the lost live studio double album Wild in Woodstock: The Isley Brothers Live at Bearsville Sound Studio 1980 -- the Isleys finally have a suitably hefty testament to their greatness.

In separate exclusive interviews with The Boombox, two key components of the Isley's legacy -- keyboardist Chris Jasper, who helped fuel the group's torrid 1970-'83 streak, and guitarist Ernie Isley, who joined alongside Jasper and continues to tour with an Isley Brothers lineup that includes founding member Ronald Isley -- look back over the decades of work summed up in the new box Album Masters, and they both used the same word to describe the sight of all these records gathered into a single collection: "Formidable."

Admitting it's "kind of surreal in a way," Jasper describes the rush of memories that came from delving back into the Isley Brothers' past for the project -- including at least one studio jam he says he'd forgotten about completely until co-producers Leo Sacks, Jeremy Holiday, and Jeffrey James dug it up during the track selection process.

"I didn't have a name for it and I think it was during the time of the World Series. So I said, 'Just call it 'World Series' for right now,'" recalls Jasper. "There was this groove. I totally forgot about it -- it's weird that something like that can just go out of your memory. And then Leo says, 'I got a couple surprises for you.' He put that on and I said, 'Wow! How did you find that?' It was funny."

"I literally just took the plastic off one today and read through some of the liner notes," adds Isley. "I'm trying to hear that live record that we did at Woodstock -- I'm hearing this for the first time since we recorded it. You hear music and it takes you right back to a particular time. It's kind of like a weird party -- you play [breakthrough Isley's 1959 single "Shout"], you come to the party and Groucho Marx is there, and Marilyn Monroe is there dancing, and JFK is there, and everyone knows the song. At some point along the way, everyone knows the music. They've been introduced to the Isley Brothers by 'This Heart of Mine' or 'Twist and Shout' or 'Work to Do' or by way of 'Between the Sheets.' 'Is that the same group?' Yeah."

As Ernie's comment alludes, the Isley Brothers' discography is incredibly vast -- so sprawling, in fact, that major chunks of it aren't even covered by this box. Although it picks up in 1959 with the release of "Shout," it skips over the decade that followed, which included several years that found the group recording for Motown -- and produced the hit "This Old Heart of Mine (Is Weak for You)" -- as well as everything that came after 1983, a time span that covers everything from "Smooth Sailin' Tonight" and "Spend the Night (Ce Soir)" to the R. Kelly collaborations "Down Low" and "Contagious."

"The only thing that I think could be better stated is the fact that our music goes beyond 1983," agrees Isley. "The hyphen -- I think the number on the other side of the hyphen should be deleted, but this is [our] CBS catalog. It's more or less a good representation."

The Album Masters box is far from the first time the group's catalog has been repackaged, but unlike standard compilations that settle for cherry picking hit singles, this collection honors the fact that the Isley Brothers were album artists whose records held together as cohesive statements. As Jasper points out, the group's early '70s streak started during a unique period in which bands like Earth, Wind & Fire, Marvin Gaye, Stevie Wonder and Funkadelic were working hard to battle the widespread misconception that black music was purely singles-driven.

"Sly and the Family Stone had kind of started it. Isaac Hayes," muses Jasper. "Albums for black artists had become important. That's what you went into the studio for — with the concept of doing an album, instead of doing a single, putting a single out and seeing how it does."

"I think for the folks that know, they know. Sometimes things have to catch up," says Isley. "Hopefully in time they will. I hope in time there will be some HBO something or Cirque de Soleil with the catalog of the Isley Brothers. That's in Animal House, that's in Sister Act. We need to do 'Shout' for the halftime show at the Super Bowl -- have everyone run out in togas, going out to the 50-yard line on all fours like Belushi."

The flip side of looking back on that bright moment in time is conceding that -- with a notable handful of exceptions that include the Roots — the number of black bands in mainstream music has steadily dwindled over the last 30 years, and it's hard to identify -- or even imagine -- a young group that might conceivably act as the next Isley Brothers.

"That's been a problem for a while," nods Jasper. "I believe it's due in part to the culture of today -- people aren't encouraged to learn how to play instruments like they were when I was growing up. I remember when it was commonplace to have a piano in the house, and someone knew how to play it. We had a piano in our house — my mother played, and she encouraged me to learn it and go learn how to read music. I learned an awful lot. My uncle was a concert violinist. It was part of our family and it was part of our lives. I think that's changed over the years."

"You know, everything sort of has a time," Isley shrugs. "Certainly, Earth, Wind & Fire are still around. War is still around. Sly and the Family Stone are still around. I think anyone that's playing, I hope they continue to keep playing -- particularly among the next generation that's coming up to their time. They learn how to sing, they learn how to play a drum kit, not pushing a button. Playing live -- that speaks volumes. For some people, that's a marvel: 'Wow! You can actually play the drums!'"

As incredible as the Isley Brothers were at their creative and commercial peak, it's arguably even more remarkable that the six-piece lineup responsible for the bulk of their greatest hits only stayed together for roughly a decade: Wedged apart by creative conflict, the Isleys splintered into a pair of factions after 1983's Between the Sheets, with Ernie and Chris leaving with bassist Marvin Isley to form the short-lived Isley-Jasper-Isley while the original trio of O'Kelley, Rudolph, and Ronald remained.

When a group has been this successful, it's incredible to think they may have left anything substantial on the table, but listening to the Album Masters box, it's impossible not to wonder what might have been.

"There's some songs that maybe we could have approached them a little differently," Jasper reflects. "There were songs that I wrote for myself and I know that I should have sung them myself, but the older brothers were more comfortable with singing. I think the Isley Brothers, as a group, kind of missed an opportunity there. We could have been a little bit more diverse. Like the O'Jays, like the Temptations, who had three lead singers. We could have explored that and made it work. As a musical group, we said 'Whoever can get the best result, let them do it.' Vocally, it should have been that way too."

Looking out over the vast array of samples that have brought the Isley Brothers' music to younger generations -- a list that recently expanded to include Kendrick Lamar's "i," which includes a piece of the group's "That Lady" -- Ernie is awed by how his family's music remains tightly woven into the cultural lexicon.

"There's a whole lot of seasoning involved. A lot of divine grace to have the longevity and the creativity and the ability to change with the musical terrain. With the musical climate," he explains, laughing about the surreal experience of checking into hotel rooms after gigs and hearing wedding parties singing "Shout" in nearby ballrooms. "The sales of the catalog are steady. It's still there. It's just wonderful to have our music continue. Our songs are still present. They're still in the room."

Musical history and cultural significance aside, what might matter most about the Album Masters box is that it's simply a lot of fun to listen to -- a genre-muddying treat that should satisfy die-hard fans while opening the eyes and ears of Isley Brothers newcomers.

"If it was food, it would be a very big filet mignon," chuckles Ernie. "Well done. No pink showing. You like steak? This is one."

See 10 Best Comebacks in Hip-Hop and R&B