Call It Metal Gymnastics

System of a Down is being stalked by Marilyn Monroe’s ghost. Not really, but the L.A. quartet finds it amusing to imagine she’s behind the room doors that mysteriously pop open in the historic Hollywood hotel where they’re hanging out.

But Marilyn didn’t even die here.

“No,” deadpans bassist Shavo Odadjian, 26, “but her ghost is here.”

That’s a pretty weird assertion, but the band is a little punchy. Having returned from touring Europe just two days earlier, the four are doing interviews to promote their highly anticipated second album, “Toxicity.” In a few hours, they’re supposed to play a free concert for hometown fans in a nearby parking lot. Then they’ll hit the road again, co-headlining the “Pledge of Allegiance” tour with fellow heavy-music makers Slipknot.

Better they should get a good night’s sleep and a week off.

Singer-lyricist Serj Tankian, 33, has a sore neck. Guitarist-songwriter Daron Malakian, 24, struggles with an upset stomach. Odadjian unexpectedly had to move into a new apartment. Drummer John Dolmayan, 27, remains polite but preoccupied, or maybe just uninterested in talking to yet another reporter.

After all, sometimes journalists make annoying generalizations about System and its aggressive sound. In a world where music is increasingly compartmentalized, its dense-yet-nimble songs are hard to pigeonhole: at once heavy like old-school metal, frenetic like hard-core punk and flavored with a wild variety of styles, from goth to jazz to ethnic folk.

The vocals veer from keening to roaring, and, although the tunes are short, they have the feel of progressive rock in their abrupt stylistic shifts, time signature changes and sometimes mystical drama.

Perhaps the music’s sheer eccentricity makes people look for other ways to categorize the band. The most common tag is “political,” because System often protests injustice, as in the new “Prison Song,” which laments the increase in inmates in the U.S., a rise fueled by mandatory sentencing for minor drug offenses.

“That is the biggest misconception,” Malakian says of this characterization. “We’re just as political as maybe the Beatles were. I’m not putting us on their level. I’m just saying we can sing ‘Ob-La-Di, Ob-La-Da,’ and we can sing ‘Revolution,’ you know?”

Besides, musical architect Malakian doesn’t consider this stuff the least bit odd. “This is pop, man,” he says. “This is, like, toned down. We’re signed to a corporate label.” He laughs crazily.

“The music could get a lot more odd.”

Previously, he and Tankian were in a band called Soil, which Odadjian managed. “We were [doing] lengthier songs,” Malakian says. “But then I started listening to the Beatles, and I said, ‘Wow, what if we had this sound, but in a song structure?’ I like structuring verses, choruses, but sometimes the verses might be a tango and the choruses might be death metal.”

If critics are confused, listeners have definitely caught on. System’s self-titled 1998 American Recordings debut has sold 750,000 copies, thanks to exposure from relentless touring plus a modern-rock radio hit, “Sugar.” Fans are attracted variously to the group’s raging sound, its social conscience and a theatrical live show in which the musicians are garishly dressed and streaked with paint, working the crowd into a frenzy with their visceral sonic ebb and flow.

Judging from the reception for “Toxicity,” which entered the national sales chart at No. 1 this month, the band will only become more popular.

“They have a deep musicality that’s really powerful,” says American Recordings head Rick Rubin, who co-produced both System albums. “For a band that offbeat, [the success of ‘Toxicity’] is really a testament to the depth of the songs,” he adds. “But also, getting a good response [from audiences] gave them the ability to open up and try different things.”

That System’s broader popularity coincided with the recent tragic events in America seems “prophetic in some way,” Rubin says, suggesting that listeners were already hungry for something more substantial than the lightweight pop dominating the charts. “It’s time to take things more seriously and to look at our world in a more compassionate way. Which is a lot of what Serj sings about.”

An even less relevant tag than “political” is one that System got early on: “Armenian metal,” based on the players’ shared heritage. Malakian was born in Hollywood, but the others arrived here as children--Odadjian from Armenia, Tankian and Dolmayan from Lebanon. All but Dolmayan attended the same private Armenian school in Hollywood. They formed System of a Down in 1994, taking the name from a poem by Malakian.

Among the tunes on the debut album was “P.L.U.C.K.” (“Politically Lying, Unholy, Cowardly Killers”), protesting Turkey’s killing of up to 2 million Armenians at the turn of the 20th century. (The Turkish government does not acknowledge the episode as genocide; Armenians maintain it was.) System also staged a benefit concert last year to help further Armenians’ position.

“To me, the Armenian genocide is personal,” Tankian says. “It’s about grandparents and things like that. [Being Armenian] indirectly and in a very deep way plays a part in everything we do, but it’s not as big as people usually make it.”

Tankian acknowledges that his heritage has shaped his character, compelling him to write such tunes as the new “Deer Dance,” which condemns police behavior at last year’s Democratic National Convention in downtown L.A. Yet there’s also “Bounce,” which he cheerfully announces is “about a pogo-stick orgy,” and “Psycho,” which Odadjian calls a sad song about coke-addled groupies.

Even more pensive is “Aerials,” a hopeful-feeling number that closes the album. It’s about how Malakian envies “simple people,” he says. “You know how we call disabled kids ‘disabled’? I think the simplicity in their minds makes them more abled than us.”

He laughs softly. “The things they can appreciate, you know?” He points to a saucer on the nightstand. “I wish I could appreciate this cup of tea as much I used to when I was a child. That simplicity is gone, as you grow up. And that has nothing to do with politics.” He laughs again, a little sadly.

This unexpectedly poignant sentiment may in part be a byproduct of the pressures System faces right now. Although well-acquainted with the demands of rising fame and willing to take them on, the players are caught between their lives as accessible underground heroes--albeit ones linked to a major label, via American Recordings’ affiliation with Sony Music--and the brave new world of mainstream popularity.

Indeed, they’re trying hard to balance all their professional and personal obligations.

As the musicians talk, friends and entourage members flow in and out of their hotel rooms. Cell phones ring incessantly, bringing calls from yet other friends who want to make sure they can get into the show, even if it’s crowded. Still, Tankian and Odadjian gamely stay on track, talking in fast, clipped sentences that mimic the cadences of their music.

“We’ll get the whole promotion thing done and get on the road,” Tankian says. “That will at least get us back on a normal type of track, even though that’s not normal in the least bit.”

But by day’s end, things won’t be even that normal. The guys won’t celebrate with well-wishers following the show, but instead will be figuring out how to replace their equipment. As the anticipated crowd of 3,500 fans swells to an estimated 7,000 to 10,000, police, fire officials and the concert’s promoter decide to cancel the gig without so much as an announcement from the stage, prompting a few hundred attendees to wreak havoc by stealing whatever of the band’s stuff they can carry, breaking most of the rest and vandalizing neighboring businesses.

If not even the band and its management anticipated just how many more fans System has attracted over the last three years, Tankian seems almost dismissive of the group’s increasing success.

“In this industry, hype can be created with a lot of money and marketing,” he says. “I find hype extremely funny.” He’s glad System moves people, “but we’re not physically saving lives,” he says. “I would prefer that Doctors Without Borders get more hype than this band does.

“People [ask], ‘How do you feel about selling [almost a] million?’ Who cares? The record company isn’t gonna pay us anyway.” He laughs. “Just kidding,” he says, then tilts his head. “Maybe not.”

Malakian finds the group’s path more difficult to fathom. “We should’ve been an indie, underground band,” he says. “The fact that this is happening to us is very odd, and we try our best not to, like, make our lives change.” He laughs nervously. “I think people see us a lot bigger than we see [ourselves].” Which is good, he says, but weird.

“Like, my friends say, ‘We hooked up with these chicks just because we said we were friends with you,”’ Malakian says. “That’s cheesy, first of all, but I was like, ‘That actually has clout?”’ He cackles, slightly amazed. “I don’t go out much, so when people tell me [stuff] like that, it’s funny.” *

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System of a Down, with Slipknot, Rammstein, Mudvayne and No One, plays Saturday at the Forum, 3900 W. Manchester Blvd., Inglewood, 6:30 p.m. $35. (310) 419-3100.