But since they won five Grammy awards -- including album of the year for their surprising collaboration, "Raising Sand" -- their names have been inextricably linked: Robert Plantand Alison Krauss. CNN: Did you have this much fun working with Zeppelin? In fact, both of us can sit there talking about music, and neither of us can recognize the artists we're referring to. I mean, all the rock 'n' roll, and black Mississippi and Chicago stuff that I go raving on about, she's going, "Hmm." Krauss: I didn't grow up on that, yeah. CNN: Your collaboration has worked out so well that you're back in the studio in Nashville, working on a second album together. If they were 20 years old and ran in Hollywood circles, tabloids might be calling them Robekrauss or Aliplant. CNN: Has he made you listen to his music collection? Plant's early blues influences included Johnson, Bukka White, Skip James, Jerry Miller, and Sleepy John Estes.

Plant, a qualified civil engineer who worked in the Royal Air Force during World War II, When I was a kid I used to hide behind the curtains at home at Christmas and I used to try and be Elvis.

There was a certain ambience between the curtains and the French windows, there was a certain sound there for a ten-year-old.

Plant, however, is 60 -- in fantastic shape, and with a full head of the golden ringlets that became his trademark during the 1970s. And while both are dead serious when talking about their craft, the rest of the time, they're like two silly junior high kids -- he, the charming prankster with a secret crush, and she, the beautiful prom queen who pretends not to be amused. " We went into the studio originally saying, "We'll give it three days and see what it's like." Plant: Alison's reputation is 24 karat, and I'm an old rock 'n' roll singer. She knew how she wanted to proceed, and we exchanged a lot of ideas musically.

Clearly, they're both having the time of their lives, and are excited about their current musical journey -- which pushes each out of their respective comfort zones and into new territory. Even the band was kind of going, "Oh wow, how is this going to work? And then we both agreed that because we both produced records ourselves, that we needed an intermediary to guide -- somebody to separate us, or to make the journey more clear. With Alison, it's letting go, and with you, Robert, it's kind of containing things.

"There's nothing worse than a bunch of jaded old farts, and that's a fact," he says.

"People who have written their story — they've gotten to the point where nothing moves.

But it was the right thing to do to do it that way. We've already been around the world, and did what we did when we were young men.

Plant: Well, we had a really good night, and we had great rehearsals, and it was very emotional -- and if you like, quite elevating.

CNN: First of all, this is the screwiest collaboration I had ever heard of. Plant: When she goes up for these wailing notes on stage, that's where I want her to go with this new project -- occasionally visit these places where she lets rip, and just lets it really come out.

Krauss (melodramatically): It's just reckless abandon!

I didn't look as good as I do now, and I didn't share the couch with another Leo. Plant: Only last week, I was being grilled again by Alison to get into shape and get it right. CNN: And in the meantime, you've been recognized by the Grammys. We've brought our gifts, and we've shared them, and the whole surrounding musically is so beautiful, that that's our reward. The fact that it wasn't some embarrassing moment of two people trying something out, and saying goodbye, and then meeting at a party years later and saying, "Oh, Christ, there's Alison Krauss!