In the late '90s, Radiohead's big-crescendo guitar-driven glory had tastemakers touting the U.K. group as the best rock band in the world. 


But with the enigmatic "Kid A" and the new "Amnesiac," recorded at the same sessions, Radiohead has generated as much confusion as acclaim. The albums are oddball indulgences of icy electronic art-rock - lonely, haunting soundscapes of beeps and pings, with Thom Yorke replacing his lustrous falsetto with alien vocals. 

The introspective works beg for undivided attention, yet that degree of difficulty has only endeared the band to an audience apparently disgusted by most current rock. "Kid A" debuted on the Billboard chart at No.1 last October and then was nominated for a best album Grammy. 

"Our music expects people to put something in themselves. Hopefully that pays back quite a few times over," drummer Phil Selway said recently. Radiohead will perform at Red Rocks Amphitheatre on Wednesday night. 

"We're in a lucky position, and it's quite liberating. We're aware that we have the trust of a lot of people, that if they listen and don't quite engage with it initially, that they will persist. It's fortunate for us that they give us the benefit of a doubt. It took us about a year and a half to get our heads around "Kid A,' and people who came to it fresh caught up a lot faster than we did. Once you find the reference points in there, it's one of those albums that gets under your skin." 

Radiohead's members first met 15 years ago at school in Oxford, England. Their first album, "Pablo Honey," was released in 1993, and the slacker anthem "Creep" became a modern rock smash. But the band was dismissed as a one-hit wonder. 

Then the keening guitar rock of "The Bends" turned Radiohead into a solid alternative act. In 1997, "OK Computer," a concept album about technology and dehumanization, made the guys a thinking-man's artistes. 

But when "Kid A" came out last year, listeners' expectations were obliterated. Gone were traditional verse-chorus-verse song structures and the band's guitar-dominated sound. 

"At the end of "OK Computer,' we were rapidly approaching a blind alley. It was the natural conclusion of one stage of our existence," Selway said. 

"We wanted to approach the next one with the attitude that we'd write in the studio, that we wouldn't be so bound by working up band performances of our songs. In effect, it was like going back to square one again, saying we wanted more options than we'd actually had for the past few years. We wanted to give ourselves the time and space to find what we wanted to do musically." 

The band assembled tracks using synthesizers and other tools of the electronica trade. The transition wasn't easy - "Kid A" and "Amnesiac" took 21/2 years to finish, and internal tensions nearly broke up the group. 

"It was quite bizarre at first, trying to find a new way that the five of us could work together, which wouldn't necessarily mean me beating skins, or everybody else playing guitars," Selway said. "Other people were bringing rhythmic ideas and sequencers along. For me, that brought about certain anxieties - "Well, does this leave me enough spacee? Do I still have a valid role in this?' 

"But it was a case of opening ourselves up to these other influences. It stretched us all as musicians and enabled us to move on." 

Cynics say Radiohead is consciously avoiding melody, but the strength of the songs on "Kid A" and "Amnesiac" is gradually revealed from the sonic characteristics. Now Radiohead is determined to pursue those impulses. 

"In the past, it felt slightly destructive at points - if it's hard going for us, it must mean that something's going wrong. No, it's just a byproduct of producing music that we're pleased with at the end. You go in the studio and have absolutely no idea how it's going to turn out, so you have to trust in the way that the five of you work together, keep that faith in yourselves that you'll achieve something that you find challenging." 

To mark the release of "Amnesiac," Radiohead is playing North American concerts, and they've been instant sellouts. 

"It's been a bit of a brain teaser at points, figuring out how we'll arrange the music so it works as the five of us playing onstage," Selway said. "Normally when we go out on tour, it's effectively producing Xerox copies of what's there on the record. 

"This time we've been able to breathe a different kind of life into the music. That's been exciting in itself."