Instead, there is usually some prevailing theme or style designated from the outset, with musicians thus contributing their own take on the central message at hand. The first such collection, 1990's Red Hot and Blue (Chrysalis), was a lively, loving tribute to one of the greatest masters of the Great American Songbook - Cole Porter - and boasted dazzling takes on the old classics by everybody from David Byrne to the Pogues (with Kirsty MacColl) to a swinging duet between Iggy Pop and Deborah Harry.

From there, Red Hot's streak has continued unabated for two decades, treating a host of different subjects and themes with similarly inspired results: Offbeat, A Red Hot Soundtrip (TVT) explored the legacy of the Beat Generation with trip-hop and ambient sound collages, while Red Hot + Rio (Antilles/Verve) and Red Hot + Riot (MCA) paid homage to bossa nova and Fela Kuti respectively.

Their latest two-disc set, Dark Was the Night, might operate from a more loosely defined central concept than many of its predecessors, but it is also one of the organization's most successful ventures so far - quite the coup, considering its 30-plus-song sprawl. With liner notes trumpeting a rather impressive A-list of indie-rock darlings - the National, Feist, Yo La Tengo, Iron and Wine - the compilation offers a modern counterpart to two previously issued Red Hot collections, 1993's post-Nirvana/120 Minutes- era time capsule No Alternative (Arista) and 1995's determinedly more nerdy Red Hot + Bothered (Reprise).

Both predecessors operated mostly as a showcase for college radio/indie artists, rather than with any statement of purpose - no governing themes, no stylistic motives. This newest collection, however, does appear to pivot around a particular theme. Overall, Dark Was the Night comes across as a baroque post-millennial take on roots music, offering plenty of moody variations on how to reappropriate older song forms for the new century. Two intriguing developments in indie rock as of late - the injection of electronic elements into folk forms, as well as the growing fixation on string arrangements and post-classical composition - also figure prominently across both discs, thus elevating these contributions from mere polite strum-and-sing territory to genuinely exciting interpretations of what the phrase “roots music” can really mean.

Both discs were produced and curated by the National's Aaron and Bryce Dessner - two of the best-connected musicians out there, if this roster is any indication. In addition to appearing on the National's contribution (more on that stunner of a song later), the brothers also lend their guitar and
bass talents to collaborations with a few other artists - and this synergetic thread runs across both discs, courtesy of various join-ups and duets and special cameos.

There are also a good number of covers here. Many of them are, in fact, the strongest tracks of all. Ultimately, despite the preponderance of slower, more introspective work, this is a compilation which seems to feed off of the thrill of collaboration, of making unexplored connections.

This bright-eyed spirit finds its ideal spokesman in the form of opener “Knotty Pine,” a joyful howl between Dirty Projectors and David Byrne, powered by thumping piano and twitchy acoustic guitar. Byrne's vocals are largely relegated to a background role, so perhaps his greater function was to bring focus to the David Longstreth-led band. The track is by far one of the most successful recordings of their career.

Equally wowing is the José Gonzalez/Books cover of Nick Drake's “Cello Song," wherein subtle electronic percolations fashion a lovely undercurrent for Gonzalez's sublimely hushed vocals. I found my heart fluttering the most when he sings along with the cello's signature refrain - gorgeous beyond belief. In the first of Feist's appearances, “Train Song” - originally done by Vashti Bunyan - the vocalist pairs with Ben Gibbard (Death Cab for Cutie) for a ghostly after-hours ramble from the loneliest of backwaters. Simple and sparse, but still spine-tingling nonetheless.

Bon Iver's “Brackett, W9” offers more of the wavering, warm-throated croon that has garnered him so many fans in such a short span of time - the melodic bass lines here give the song a nice buoyant quality, also helped along by the use of occasional watery electronic textures underneath. And yes, knees will inevitably buckle when Justin Vernon heaps vocal harmony upon vocal harmony - a chorus of cabin romantics. The effect is wonderful.

Grizzly Bear's “Deep Blue Sea” is absolutely magical, a shimmering web of ebb-and-flow vocals, spooky whistling, elegant guitar strums, and strangely disembodied hand claps echoing away in the background. I'm torn as to whether I prefer this track, or the Grizzly Bear/Feist collab that appears later on the disc, “Service Bell.” Building slowly and steadily from brushed drums and gently whirring atmospherics, the song eventually gives way to a dramatic release in the form of lovely harmonized howls and a rhythm akin to the sound of a giant's footsteps. Lasting less than two and a half minutes, it's quite the ravishing little epic. That being said, top honors for "packing a serious emotional punch in very little time" goes to Iron and Wine's minute-long masterpiece-in-miniature “Die," the latest piece of evidence from Sam Beam that sometimes a man alone with his guitar is really all that's needed to break a heart or two.

Speaking of heartbreak: Antony teams up with Bryce Dessner for a wistful, impeccably phrased take on Bob Dylan's “I Was Young When I Left Home," thus reminding listeners that while the most sublime of modern torch singers might prefer piano accompaniment, he still devastates just as thoroughly with the aid of an acoustic guitar. Dylan's song has an older-than-the-hills feeling to it, as if it could have been written centuries ago, handed down from troubadour to troubadour. Antony understands this, and treats the composition with reverence and - as expected - an immeasurable depth of feeling. The Kronos Quartet pull off a similar feat - and without words, no less! Their cello/violin/viola overhaul of the Blind Willie Johnson antique-blues classic “Dark Was the Night, Cold Was the Ground” is alluringly murky, soulful, and downright damaged. Sure, the lyrics are missing, but the intensity remains.

As I said earlier, inspired cover songs abound: My Brightest Diamond's treatment of the perennial Nina Simone favorite “Feeling Good” offers an abundance of elegant tension, along with Shara Worden's icy yet curiously comforting vocals. It's a fine example of an artist staying true to the original - check out the swanky horns and sumptuous strings for evidence - while still managing to invest it with something altogether new and different.

Similarly, Sharon Jones and the Dap-Kings remake Shuggie Otis' masterstroke of easygoing funk, “Inspiration Information” in their own image, retaining the original's confident strut but inserting a potent rolling bob-and-weave rhythm and the band's familiar punchy, precise horn fills. Jones sounds decidedly more grounded than Otis ever did, however, and so those accustomed to the song's hazy vocal delivery will be pleasantly surprised by the earthier reading she brings to the song. By the time she gets to the cries of “jumpin', laughin', smilin', havin' fun," it's pretty obvious that's what's going on here.

Dave Sitek (TV on the Radio) appears to be doing all of those same things on his delightfully touched-in-the-head reading of The Troggs' “With a Girl Like You," trading in the original's sloppy garage-y charms for a dense fuzz of spacey synth sounds - layers of 'em, as expected, if you've followed his band's career - and considerably less excitable vocals. Oddly serene vocals, actually - though Sitek is clearly have a blast here, reveling in having created something so vastly different from the original version.

The Dessner brothers unite with their bandmates on a new recording from The National, “So Far Around the Bend," a woodwind-draped tale of fond remembrances for a long-lost love and nostalgia for the '90s. “Pray for Pavement to get back together," vocalist Matt Beringer pleads at one point. It's a lush, swoon-worthy gem - not only is their familiar arranger/sonic wizard Padma Newsome present (lending backing vocals), but modern-composition composer (and Bjork/Antony collaborator) Nico Muhly has put together a lovely orchestral arrangement as well.

Newsome also contributes a curly-tendril-ed string arrangement to the Aaron Dessner/Justin Vernon falsetto-fest “Big Red Machine” - as one could probably guess, the results are superb. Another jaw-dropping team-up is the pairing of Blonde Redhead with the sadly lesser-known Australia-to-Berlin mood-makers Devastations. Their joint composition “When the Road Runs Out” rings true to each band's sensibilities and thus, through the blend of seemingly disparate elements, crafts an altogether different sound for each. Erotic but nervy, loaded with eerie clip-clop percussion, bells, and odd hums and squeals, the song could soundtrack a Bernardo Bertolucci/Wim Wenders film, if you could imagine such a thing.

Sure, Dark Was the Night contains a few missteps - the usually reliable Arcade Fire come across as pale imitators on the underwhelming, where's-the-bluster “Lenin," while Sufjan Stevens' ambitious, frequently impressive 10-minute epic “You Are the Blood” (based on a composition by Ray Raposa of Castanets) sticks around for about a minute or two longer than necessary.

Still, there are highlights to be found all across both discs - after all, I didn't even mention My Morning Jacket's Desire-era Dylan vibe of “El Caporal," or Spoon's stripped-down rubber-band jerk-pop of “Well-Alright," or Yeasayer's delirious cosmic polyrhythm-thump on “Tightrope."