"We weren't looking for three from different generations, we weren't even trying to cover any bases," Guggenheim said. "We were just trying to find three really fascinating people who are still searching and still trying to tell their story."

SIMILAR SHADES OF BLUES

As it turns out, Page and White had plenty of common ground, a passion for the blues. And White, of course, was raised on Led Zeppelin.

"They're the biggest explosive supernova that happened to the blues since Robert Johnson in the last hundred years," White told Reuters. "No way to ignore it."

Page said he had not heard any of the White Stripes' dissonant, blues-punk music before he saw them perform with his former bandmate Jeff Beck in London, in 2006. But he quickly caught up and became a fan.

That left the Edge, whose band developed as rejection of white-boy blues bands, as a potential odd-man-out.

"He was more au fait (with musical traditions) than possibly I thought he would have been," said Page.

Indeed, the Edge's manipulation of guitar tones left a positive impression on White, who will have to save his boxing gloves for another occasion.

But Page and White were cagey on whether the filmmaking experience would lead to additional collaborations such as a tour or album.

"There's a lot of things we could do," said White, who already plays with two other side projects. "I don't think any of us would do it just to do it, because it would make a splash. It has to have a context."