Illustration by Michael Renaud

In January, I saw an unforgettably strange concert at the small NYC theater Le Poisson Rouge. Andrew W.K.-- party-rock force of nature and living animated .gif of a David Lee Roth jump-kick-- shared the stage, or jostled maniacally for it, with the Calder Quartet.

The quartet opened with the glacial, half-hour-long piece "Cadenza on the Night Plain" by minimalist composer Terry Riley. So it was like cold water to the face, then, when Andrew W.K. lunged out afterwards, even if we all knew he was coming. He plunked himself down at a grand piano, fumbled through some jokingly botched Bach, and then launched into what the program called "Spontaneous Piano Improvisations": something like Scott Joplin rags after several hundred lines of blow. He conscripted the Calder Quartet to provide back-up arrangements to several of his songs from I Get Wet, during the choruses of which we were invited to make silly animal noises. The proceedings concluded with a solemn observance of John Cage's "4'33"".

The concert was a hilarious, confounding experience-- a half-joke, though it was impossible to say for sure which half. Who was the concert for? Was the intention to trick the W.K. faithful into soaking up some Terry Riley? Or was the idea to let loose a fire hose of bad manners on the modern-classical crowd?

In fact, it was neither. The unlikely partnership represented something fascinatingly close to "business as usual" for the small, but steadily growing, indie-classical scene. Groups like the Calder Quartet, which perform alongside W.K. (or Airborne Toxic Event or the National) as often as they play recitals of Brahms and Bartók, are increasingly common. Contemporary-classical ensembles like yMusic, meanwhile, carry around stamped-up genre passports bearing collaborations with Arcade Fire, Grizzly Bear, and Sufjan Stevens alongside more conventional modern-classical fare. Rock musicians such as Jonny Greenwood, My Brightest Diamond's Shara Worden, and St. Vincent's Annie Clark pen full-fledged classical compositions, and no one bats an eye. For anyone trying to sort through genres to assign team jerseys, it's a mess, and often a glorious one.

Lately, it's become hard to even tell an

indie rock musician and a composer apart.

This development has been fascinating, puzzling, frustrating, and heartening to watch from the unique vantage point of New York City, where places like Le Poisson Rouge have built themselves up by serving as the crossroads for all this activity. Over the past decade, indie-classical has grown past the point where it's some miraculous new fruit on pop culture's Big Tree. It's a high-functioning cottage industry now, complete with its own roster of independent labels (New Amsterdam, Innova, Cantaloupe, Bedroom Community), familiar names (Nico Muhly, Hauschka, Owen Pallett, and Missy Mazzoli of Victoire, to name a highly visible few) and a round-the-clock PR department. Moments like Joanna Newsom's 2007 concert with the Brooklyn Philharmonic used to feel rare. Now, something like it seems to come along every month.

It certainly hasn't always been this way: it used to be that composers mixing rock and classical, or inventing new forms-- minimalists like Philip Glass, Steve Reich, and La Monte Young, composer-collectives like Bang on a Can, experimental improvisers like John Zorn-- operated like revolutionaries, staging concerts in hot, cramped basements for a dozen friends while the larger classical music industry continued unabated above them. But what used to be called the Downtown NYC scene has gentrified, much like actual Downtown New York: David Lang, one-third of Bang on a Can, won a Pulitzer several years ago. Carnegie Hall now clamors for Steve Reich premieres. Philip Glass is, well, Philip Glass.

Born of these advances, the new generation is pouring in: eager, collaborative, as invested in indie rock as they are in the nuts-and-bolts arcana of composition. Lately, it's become hard to even tell an indie rock musician and a composer apart. Take Tyondai Braxton, for example, who left his innovative rock group Battles to explore wilder, weirder pastures with his solo album Central Market. Or Owen Pallett, who makes dense, ambitious, highly unclassifiable singer-songwriter records as often as he arranges strings for more traditional bands. This scene is resourceful, optimistic, and building on the best lessons their teachers gave them. Stick together. Do as many different things as you feel like. Don't worry about big organizations. Make it happen yourself.

The biggest distinguishing mark of the indie-classical

scene is its lack of distinguishing marks. This is music

that does not have to argue for its very right to exist,

which means its free to smear the borders of form.

The music these younger artists are producing thus far, however, bears few of the pointy, manifesto-ish edges of their forebears. Downtown NYC's seminal pieces often bore the pressurized marks of the politicized time in which they were made, a contentious moment in which nearly every composition also made an implicit argument for what kind of music was OK to write. But the biggest distinguishing mark of the indie-classical scene is its lack of distinguishing marks. This is music that does not have to argue for its very right to exist, which means its free to drift into dreamy cul-de-sacs, to explore drift and texture, to smear the borders of form. These artists can record albums without having to pause to consider the implications.

This freedom has enormous advantages as well as small, nagging drawbacks. Contemporary classical, in all its forms, has now moved its way closer to the center of the cultural conversation than at any point in decades. The tent of indie-classical has grown to the point, in fact, where there is almost as much dross populating the sphere as there is excellence. On my best days, I see the kind of development I desperately yearned for while attending another orchestral concert where the energy flickered like a dying bulb: a Petri dish of eclectic interests, swarming with potential. On my more cynical days, I see a group of talented musicians who are endlessly congratulating themselves for existing, turning out fairly interchangeable, faceless music that often dissolves into dulcet murmuring on contact.

When I spoke to the three founding members of Bang on a Can last year, on the occasion of their label Cantaloupe's tenth anniversary, Julia Wolfe reflected on the downsides of finally being surrounded by like minds after years of fighting and isolation. "We're really lucky that times have changed," she said. "But there was something interesting about being in that difficult time, the severity of early minimalism, especially. It was so radical. The early works of Reich, and Glass, and the work Meredith Monk was doing-- there was an incredible excitement then about tearing things down and building them up. It wasn't as friendly of a time. I think people felt much more isolated. Now, from indie-rock guys writing for the concert hall to the concert hall writing for indie rock bands, it's very open and much more liberating. But there's something to be said for the tension, too."

The challenge for indie-classical, then, is the same one indie-rock faced down over the last decade: If there's no grand cultural war left for you to wage, how are you supposed make friction? Indie rock responded by fanning out into a thousand sub-genre deltas, each with their own set of reference points. The best stuff, every year, is the stuff that somehow leaps across those gaps, like a firing synapse. So it goes with indie-classical: the scene has grown to the point where a guided tour is necessary.

Below, you'll find a brief aerial view of what you've been missing-- five records resourceful enough to throw off their own sparks. Also, listen to an indie-classical playlist at Spotify.

David Lang: This Was Written By Hand

As one-third of the composer-collective Bang on a Can, David Lang is something of a genial father figure of the indie-classical scene. Talk to any of the world's main players and you're likely to hear them tell you about their life-changing stint in Bang on a Can's summer festival, which has acted as a sort of feeder school and incubator for the group's try-anything mentality. Lang's music has undergone many stylistic shifts over the years: In the 80s, he wrote bristlier stuff, but in the last decade or so, he's shifted quietly into a more pensive register. The Little Match Girl Passion, his 2008 work that won him a Pulitzer, was written for only four voices and some hand bells. This Was Written By Hand, his most recent recording, is a collection of short solo piano works played by the British pianist Andrew Zolinsky.

The album holds the same, sustained melancholy mood: thoughtful, searching, elegiac, minimalist. Lang's way with repetitive phrasing doesn't feel like that of minimalists like Glass or Reich's, though. When his works linger over and repeat a figure, as on the title track, it feels uncannily like a puzzling notion being considered by an inquisitive, slightly neurotic mind. In that respect, Lang's music mimics the intellectual sensation of thinking and writing about music as much as it does the act of listening to music itself. To immerse yourself in this music is to hear a mind's churn. It can be perversely soothing.

Kitchener Waterloo Symphony/Nico Muhly/Jonny Greenwood/Richard Reed Parry: From Here on Out

That this album-- which includes compositions by Radiohead's guitarist Jonny Greenwood, Arcade Fire's Richard Reed Parry, and indie/classical ambassador Nico Muhly-- comes bearing a softly-lit close-up photo of the orchestra's music director Edwin Outwater looking like Patrick Swayze at the end of Ghost says a lot more about the curious marketing peccadilloes of the traditional orchestral marketing world than it does about the music contained within it. In earlier times, a record featuring the contributions of rock stars was more likely to be a lamentable but necessary cash-in; the genre divides were just too wide.

That this record is so formidably dark, unsettling, and substantive, then, is indicative of the shifting culture. If you feel as though you recognize the air of free-floating malevolence that marks Greenwood's "Popcorn Superhet Receiver", it's probably because sections of it were re-appropriated for his film score to There Will Be Blood. Greenwood knows, like Polish composer Krzysztof Penderecki or Hungarian master Gyorgy Ligeti, that a hovering cloud of semitones do an excellent job of suggesting cancerous evil. Greenwood uses this hackle-raising technique to carve out a series of moans, whoops, and imploded shrieks in the orchestra, with strings peeling nastily away from each other like swarms of wasps.

Richard Reed Parry, who can normally be found onstage, switching wildly between accordion, celesta, drums, double bass and more with the Arcade Fire, provides a breath-caught, convincing simulation of a fluttering heart and jagged, queasy breaths on "For Heart, Breath, and Orchestra". The work comes framed with a neat concept: "The performers wore stethoscopes positioned over their hearts in order to play along with their own heartbeats. Additionally, the soloist was at time required to play in perfect synchronization with his breathing," Parry writes in the liner notes. This destabilizing compositional trick lends a fascinating feeling of irregularity to the piece: it shifts, heaves, and stumbles unexpectedly. It sounds palpably frightened. It feels alive.

Nico Muhly, who has worked with indie-rock artists for years alongside a more traditional composer's career, provides the title piece and a glittery short work called "Wish You Were Here". "From Here On Out" opens with the sound of a single violin tracing a fleetly pulsing figure while string and horn sections blow gusts behind it before downshifting quickly into a series of little halts and shudders, premonitions and hints thrown out darkly against a background of suspicion. Muhly has a marvelously attuned ear for color, and both "From Here On Out" and "Wish You Were Here", which riffs on the textures and sounds of a gamelan ensemble, shimmer and murmur with a thousand shades.

Chiara String Quartet/Matmos: Jefferson Friedman: Quartets

Jefferson Friedman is friends and colleagues with indie-classical fixtures like Nico Muhly, but his music quite definitely does not resemble theirs. There is very little in the way of glassy, narcotic repetition, or the incremental building and exploring of a single mood that characterizes a lot of his colleagues' work. These pieces are defiantly old-fashioned in the best possible sense: They could be string quartets written in the 20s. But something ineffably "off" in the progression of voices signifies that Friedman is writing now. His songful quartets earnestly probe small-scale modern human emotions: nagging doubt, creeping unease, simmering anger. Anyone with a love of Rachel's could quite easily find their way around in here. On the second half of the disc, Matmos step in to perform their demented-forensic-surgeon routine, ripping the pieces up by their nerves and tendons, a squirm-inducing but fascinating listening experience.

Lawrence Ball: Method Music

The sexy lede buried beneath the almost comically dry title of this record is twofold. 1) It is a collaboration between the mathematician/composer Lawrence Ball and Pete Townshend, and 2) It represents the at-least-partial realization of one Townshend's most dearly held fantasies, a rock opera called Lifehouse that was to use synthesizers as a way to to produce music tailor-made to a specific user's input. The Lifehouse project is one of those Smile-like ideas that tend to strand grand-thinking rock musicians on sharp rocks, but the idea involved creating musical software that would be free to users, who would feed the software specific input and watch as it produced a brand-new piece of music specifically for them.

Because it's always better to take a person for a ride in a sports car than to spend hours detailing the features of its engine, Ball and Townshend show you exactly how the process feels: the lead-off cut on this monumental two-disc set is "Baba O'Riley", fed through Ball's software. What emerges on the other end is wondrous, rippling, and startlingly tactile music. There is no math in the listening: It's like watching a brightly colored pinwheel turn faster and faster until it appears suddenly to revert in the other direction.

Lisa Moore: Lightning Slingers and Dead Ringers

The New York-based Australian pianist Lisa Moore is a tightrope-walker, a daredevil. She's the best kind of contemporary classical musician, one so fearsomely game that she inspires composers to offer her their most wildly unplayable ideas. She can play them all. Her albums are like the equivalent of casting yourself in a Lars von Trier movie: You have knowingly signed up for a hellacious physical and spiritual beating in the service of Art. One of her signature pieces, Don Byron's Seven Etudes, puts the pianist through a theater-of-pain demonstration in arrhythmia: pounding out one rhythm with her hands, she sings a series of "la-la-las" completely at odds with the piano. It's a gripping demonstration.

Her latest record, Lightning Slingers and Dead Ringers, is a dense, fiendish record that might appeal to devotees of Nine Inch Nails' The Downward Spiral. The composer Annie Gosfield doesn't just provide a loop of electronic sampled noise for Moore to accompany on her piano, she makes Moore play the sampler and the piano herself-- a fact that becomes doubly mind-blowing when you listen to the record. The looping tones that ground this piece are some nasty shit: The gurgling synth loop on the second movement, "Languid and Layered", wouldn't be out of place on a Cash Money record. While this cacophony resounds, Moore hammers out high, brittle accompaniment on the piano. The interplay of the two is some of the most genuinely demonic-sounding music I've heard all year. But please, for the love of God, don't put this on while you are cooking... or during dinner, or when you are trying to read. It would be like knocking loose a cage of tarantulas in a closed room and then lying down to take a nap.