TORONTO -- It wasn't billed as such, but Wilco's show last night at Toronto's Phoenix Concert Theatre was more than just a concert; it was also part of an experiment.

The group's current tour could be viewed as field research into how music makers will operate in what pop-culture historians will one day characterize as the post-major label period; a time when the business end of the music business has forfeited any semblance to being involved in a creative endeavor and artists are being left to forge their own relationship with their audience.

Some background: Wilco, viewed by many fans and critics as the kingpins of a small-scale music insurgency characterized as "alternative country," has a new album in the can, titled "Yankee Hotel Foxtrot." It is a record that is challenging, confounding and often brilliant. Their label, Reprise Records (part of the AOL Time Warner concern) judged the set to be unworthy of release. This triggered Wilco's departure from Reprise, and they are now testing the waters of free-agency, with numerous suitors said to be eager to sign the band (and a release now expected in the new year).

But there's a hitch. "Yankee Hotel Foxtrot" has leaked out through the internet and MP3 copies of the songs have spread like Ebola. "Do you all have our new record,? Did you download it? Thanks!" Tweedy asked the Phoenix crowd last night, and it was difficult to tell whether his gratitude was sincere or sarcastic. But he may be just as uncertain about the merits and liabilities of fans taking control of the music's manufacture and distribution. Everybody is travelling in uncharted waters here.

Record industry wisdom will tell you that circulating an unreleased album that widely through the internet will destroy any hope of selling the record to fans - an argument that assumes a fan who is so frantic to hear Wilco's new record, he or she will seek out unavailable music, download it, decode it and burn it, but won't further part with ready cash to fetch the disc once it arrives for real at retail.

But what if Wilco's whole experience with "Yankee Hotel Foxtrot" -- including refusing to compromise on making the record more commercially palatable -- actually enhances their cachet among fans and galvanizes a relationship with their admirers, a relationship that is conducted beyond the auspices of a multinational media corporation? Or, as band-leader Jeff Tweedy reportedly told the crowd at an earlier show on the tour: "You don't need a label to make music."

So time will tell whether the "YHF" experience is Wilco's triumph or undoing, but , based on what went down before a packed crowd of fans at the Phoenix Thursday night, the edge would appear to be on the triumph side.

Amid all the other question marks surrounding Wilco, there was the added tension of breaking in a new lineup of the band. Gone is drummer Ken Coomer and guitarist Jay Bennett, replaced respectively by percussionist Glenn Kotche and Leroy Bach, who has previously served as touring keyboardist/guitarist with the group. But the new lineup and new songs seem to have inspired Wilco to rethink its sound from the ground up. "Yankee Hotel Foxtrot" sees Tweedy and company appending their characteristically rootsy sound with limber polyrhythmic accents and all manner of analog-electro squiggles and burps. But in concert, those jarring flourishes were most often seamlessly incorporated in the group's sound.

Wilco's new music is built on the bedrock of Tweedy's gruff but expressive voice and rudimentary guitar. Although most musicians avoid the strain of live performance by pitching their songs in a lower key, Tweedy delivered "She's A Jar" and the new number "Kamera" in a voice that was even more strained and keening than on record. Here, long-serving bassist John Stirratt stepped up his game too, teaming up to duet more frequently with Tweedy.

And while Tweedy's guitar-playing won't keep Jimmy Page up at night, his solos on "I Got You (At The End Of The Century)" and "Monday" were full of character and style, if not virtuosity. Likewise, an encore of "Sunken Treasure" found Tweedy plucking out a faltering solo that gradually gathered momentum and led the band into a white-noise charge to the song's climax. "I'm The Man Who Loves You" holds the new record's most buoyant melody, but Tweedy fractured the song's pop potential with an unhinged one-note solo. Even when Blue Rodeo's Bob Egan (who toured with Wilco circa '96) ambled onstage to squeeze some sparks from his axe during "California Stars," Tweedy countered with his own deft turn.

Although Coomer's ouster from the drum throne has been viewed askance by some fans, it would be hard to find fault with Kotche, as inventive a drummer as one is likely to see in a rock group. Whether tossing in xylophone accents into the new number "I Am Trying To Break Your Heart," providing a hearty thump behind "Shot In The Arm" or laying back during a loose singalong version of "Passenger Side," Kotche's diverse skills make him an obvious asset.

If there was a centerpiece to the show, it came at exactly the half-way point in the 22-song, two-hour set, when the quartet launched into "Yankee Hotel Foxtrot's" most challenging song, "Ashes Of An American Flag." The number built at a somnolent pace until Tweedy declared: "I would like to salute the ashes of American flags/And all the fallen leaves filling up shopping bags." At once, the song spiraled into cacaphony, with Tweedy strangling a frighteningly atonal, protracted solo from his instrument.

The careful listener couldn't help but consider the lyric and unexpected violence of the music and flash on the horrors of Sept. 11 in a way that was more visceral and meaningful than all the sanctimonious tributes and dedications of recent weeks. That kind of expression is a tall order for any kind of music, but Wilco is up to the task, and hopefully it's something that a lot more people will discover whenever, wherever or however "Yankee Hotel Foxtrot" is finally released.

The offbeat quintet Elf Power opened the evening with an uneven set of unvarnished guitar pop built around the unlikely lineup of bass, guitar, drums, accordion and cello. Things only really caught fire towards the end, when the squeezebox and bow were set aside and the group reconfigured for a three-guitar attack, peaking with a speedy cover of Brian Eno's "Needle In The Camel's Eye." (More on: Wilco).