BY JIM DeROGATIS POP MUSIC CRITIC

At a time when few artists can hold an audience of 20,000 with the strength of their music alone, Neil Young and Pearl Jam stand as unique concert experiences. Though the phrase has always been essentially meaningless as a genre tag, Young has often been called "the godfather of grunge," while the Seattle quintet was one of the sound's most successful purveyors when it burst on the scene in the early '90s. Of course the two collaborated on a generally underwhelming album, "Mirror Ball" (1995).

After Dylan, Young remains the most vibrant icon of the '60s, while Pearl Jam is now an anachronism of Generation X (its 17 million slackers having long since been eclipsed by the 72 million cheerful consumerists of Generation Y). Despite the generational split, their connections run much deeper.

Both acts have had famously contentious relationships with the music industry. There was Young's celebrated feud with Geffen Records in the 1980s, when the company sued him for making a series of albums that didn't sound like Neil Young. (While it's difficult to feel sympathy for David Geffen, in retrospect, it's hard to blame him: When was the last time the most diehard fan listened to "Trans" or "Everybody's Rockin'"?)

For its part, Pearl Jam famously took on the monopolistic giant Ticketmaster, fighting for more reasonable service charges for its fans, and ultimately losing when the Justice Department, which originally approached the band to file a complaint, opted out of taking any action on it.

At the same time, the group balked at the hype machine of the industry in the '90s, refusing to make videos after the multi-platinum smash of its breakthrough album "Ten," criticizing the cookie-cutter nature of modern-rock radio (and running its own pirate station from the parking lot at gigs), and drawing back from talking to the press.

(In their typically cantankerous fashion, both Young and Pearl Jam singer Eddie Vedder, an Evanston homeboy, declined to be interviewed by the Sun-Times.)

In recent years, Young's anti-commercialist stance (remember the video for "This Note's for You," which was banned by MTV?) has been undermined by his hypocritical decision to tour under the aegis of Clear Channel, which champions "cross-promotional synergy" and nearly tripled the price of his concert tickets. (The best tickets for Young's show this week cost $85, while Pearl Jam is charging $35 across the boards.)

Pearl Jam, meanwhile, is growing even more hardcore. Last weekend, the group announced that it has fulfilled its commitment to Epic Records, the company that's been its home throughout its career, and it has no plans to sign with another major label.

The band has been edging away from the traditional record company model for selling its music for some time now, issuing double live CDs from every show on its 2000-2001 world tour and moving some 1.3 million units largely through its own Web site. If the group does indeed avoid signing with another label, it will be the first major rock act to attempt to use the Net as a D.I.Y. alternative to the music business as usual.

But perhaps the most significant connections between Young and Pearl Jam can be found in their respective followings--both have devoted to near-obsessive fan bases dedicated to trading and collecting bootlegs of their concerts, where they are rewarded with dynamic and ever-changing performances--and in their stubborn insistence on following their own paths in the recording studio, for better or worse.

While the artists' disdain for trends and refusal to tailor their music to the demands of the marketplace is admirable on one level, it's hard to deny that it's been a long time since either made an unconditionally, beginning-to-end great album. Young's last unqualified masterpiece was "Ragged Glory" (1990), while skeptics say it's been all downhill for Pearl Jam since "Ten" (1991), with every subsequent release, including last year's "Riot Act," including at least as much uninspired filler as propulsive rock.

So what can we expect Tuesday and Wednesday?

The good news about Young is that he is touring with Crazy Horse, which has always been the best (and loudest) of his many live incarnations. The bad news is that he will be performing in its entirety an epic concept album called "Greendale," which isn't even scheduled for release until September, when it will be paired with the DVD of an original film that the artist shot himself on Super 8.

These are not good omens. Young has an abysmal track record when it comes to movies--his previous directorial efforts, "Journey Through the Past" (1972) and "Human Highway" (1982), are both notorious dogs--and the story of the fictitious small-town "Greendale" seems fairly inscrutable, involving eco-terrorism, the shooting of a pet cat by the FBI and several cameo appearances by Satan.

The 57-year-old singer and songwriter has been taking pains to explain the plot of his two-hour work with onstage monologues that have been as long as some of the songs, according to published reviews. And the tour reportedly features full-sized stage sets, live actors and video screens to forward the story.

Wrote Florida critic Bill DeYoung of June 8's opening show in West Palm Beach, Fla.: "The unfamiliar music--beautifully executed though it was, and played with trademark precision--left many people scratching their heads." (Young turned to standards only during a four-song encore.)

Though there's been some controversy surrounding Pearl Jam's recent shows--thanks to Vedder's anti-war monologues and performances of the political toss-off "Bu$hleaguer"--the group is offering a more crowd-pleasing set, alternating favorites such as "Corduroy," "Alive" and "Even Flow," with newer tunes from "Riot Act" and "Binaural" (2000), and stretching out into instrumental jams that extend many of the tunes to five or six minutes.

Still, some believe that the group is running on empty. Wrote Hollywood Reporter critic Erik Pedersen of a recent California tour stop: "Pearl Jam was just OK. Even when they paraded through the hit list, something was missing."

The advance word from naysayers aside, if there's one more connection between Young and Pearl Jam, it's this: Both artists retain the ability to defy expectations and thoroughly surprise us. For Chicago fans, the final word on their 2003 tours won't be in until both concerts are history on Thursday morning.