R.E.M. was at the height of its powers when it ventured into the studio to record its first "MTV Unplugged" session in 1991.

The legendary Athens, Ga., band -- consisting of drummer Bill Berry, guitarist Peter Buck, bassist Mike Mills and singer Michael Stipe -- had just released "Out of Time," a work of uncommon beauty and bold ambition that would firmly establish R.E.M. as one of the biggest acts on the planet.

It was a very different R.E.M. that returned to tape a rare "Unplugged" encore in 2001. It had lost one of its original members -- Berry, who suffered a brain aneurysm onstage in 1995 and retired from the band two years later -- as well as much of its sales power. Its then-current album, the gorgeous "Reveal," managed to go gold but was still seen as a major commercial disappointment in comparison to such multiplatinum triumphs as 1992's "Automatic for the People" and 1994's "Monster."

In this 1994 file photo originally released by Warner Bros. Records, alternative rock band R.E.M., from left, Mike Mills, Michael Stipe, Bill Berry, and
In this 1994 file photo originally released by Warner Bros. Records, alternative rock band R.E.M., from left, Mike Mills, Michael Stipe, Bill Berry, and Peter Buck are shown when they released their new album "Monster." (AP Photo/Warner Bros.) (Anonymous)

Yet both "Unplugged" outings were equally glorious affairs. And "Unplugged: The Complete 1991 and 2001 Sessions" offers invaluable evidence that R.E.M. deserves to be ranked as the greatest American rock band of all time. I can't tell you how long I've been waiting for these acoustic recordings to be "officially" made available to the public. (Yes, I know that bootlegs have been around for ages.)

So I was thrilled to hear that the always-fabulous Rhino record label was offering up this "Unplugged" collection as a limited edition four-LP set for Record Store Day, the annual celebration of independent music retailers that took place in April.

But, of course, not everyone digs vinyl (or has a record player).

So, it's nice to see that this set is also being released on CD ($24.98) and in digital download formats on May 20.

Fans should really enjoy this striking set, which includes every song from the original TV broadcasts as well as 11 cuts that were never aired.

The first 17 songs hail from the 1991 "Unplugged" set. The band sounds at ease in the acoustic setting as it tackles "Out of Time" material, including the megahit "Losing My Religion," as well as old favorites like "It's the End of the World as We Know It (And I Feel Fine)." The group travels all the way back to its 1983 debut, delighting with "Perfect Circle," and even includes a memorable cover of the Troggs' "Love Is All Around."

If you only plan to purchase a couple of tracks from the 1991 batch, when it becomes available for download, I recommend going with "World Leader Pretend" and "Fall on Me." The former really benefits from the acoustic setting, sounding even more satisfying than the original version found on 1988's "Green." The latter is even more stunning, with Stipe's vocals soaring, aching and soothing in ways that are nothing less than astounding.

The 2001 tracks are just as magnificent -- in some cases, even more so. The band does a great job re-imagining some old favorites, including "Country Feedback," "So. Central Rain (I'm Sorry)" and "The One I Love," but the newer material sounds even stronger.

That might surprise those who lost track of R.E.M. after its commercial heyday in the mid-'90s. Yet the band produced some of its very best material later in its career. The proof can be heard on the "Unplugged" versions of "At My Most Beautiful" "Daysleeper," "Electrolite," "Imitation of Life," "I'll Take the Rain" and other offerings from 1998's "Up" and 2001's "Reveal."

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