POP MUSIC REVIEW : Rocking the Stocking : Alanis Morissette throws a curve in a strong ‘Almost Acoustic’ performance. Porno for Pyros and Sonic Youth also offer challenging sets.

So much for those who have summarily dismissed Alanis Morissette as a one-dimensional artist.

Taking full advantage of the platform offered by KROQ’s annual “Almost Acoustic Christmas” benefit concert at the Universal Amphitheatre on Sunday, the young Canadian showed that there’s more to her than even many fans expected.

Many in the audience were clearly primed to pump their fists and chant along to Morissette’s vituperative kiss-off hit, “You Oughta Know.” Instead--in what was far and away the top moment of a show also highlighted by challenging performances by Porno for Pyros and Sonic Youth--she threw them a curve.

All dolled up in an elegant black satin gown and seated on a stool, Morissette took the song’s rage and bitterness and turned it into a display of control and sophistication. Her solid four-piece band played acoustically (rare on this night, despite the show’s title) and was augmented by a string quartet and pianist.

Rather than softening the song’s withering bite, the delivery made it all the more barbed--even if some in the audience seemed puzzled at her refusal to let them revel in the recorded version’s yelps and naughty words.

On the first of two nights for the sixth annual seasonal fest, the biggest shows of audience enthusiasm came for the acts that presented the least challenging sets, and vice versa. Most unimaginative was the English band Bush, which didn’t alter its pseudo-Seattle rock one whit in recognition of this special occasion. Humbug to them.

The Foo Fighters did a bit more to earn their acclaim, increasing the punk quotient of its power-pop. Joan Osborne offered the evening’s one other really acoustic set, striking an almost Carole King-like tone. Garbage’s performance showed singer Shirley Manson to be a compelling presence, though her shimmying seemed totally disconnected from the songs’ cutting lyrics. And the goofy Presidents of the United States of America made for a charming diversion but nothing more.

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The crowd was warm but hardly boisterous as Perry Farrell used the setting to introduce the new format of his Porno for Pyros, its swirling jumble of Mediterranean-tinged alterna-rock exotica given a new potency by the presence of temporary bassist Mike Watt.

Farrell himself was a genial, subdued host, toasting the fans with a bottle of wine and earning goodwill for his hard-to-peg music by capping it off with a richly textured rearrangement of “The Mountain Song,” a fan favorite from his old band, Jane’s Addiction.

Sonic Youth found goodwill a bit harder to come by, but then the New York band didn’t really try, giving over about two-thirds of its 20-minute set to a free-form feedback extravaganza. Cheers came when the stage rotated to take the quartet away.

If that was rude of the audience, it was nothing compared to the reception for the brief set by Wesley Willis, a Chicago street artist and a current rock underground cause celebre.

Although KROQ fans generally embrace performers who present a semblance of a troubled soul haunted by demons, some apparently weren’t so ready for the real thing. Willis, who has long battled mental illness, sat stockily behind his electronic keyboard and, using the machine’s factory-programmed demonstration tunes, crudely delivered three virtually identical songs, including two new entries to his ever-growing roster of tributes to rock performers whom he admires and/or who have befriended him. This night’s honorees were Morissette and the Presidents.

It’s the musical version of primitive art, but about a third of the fans on hand appeared to be the real primitives, squirming in their seats and shouting for Willis to leave the stage. If Santa was paying attention, there will be coal in their stockings.