The pairing of rock icon Robert Plant and Alison Krauss has proved to be a match made in music heaven. Such a great match, in fact, that they're following their 'Raising Sand' duets album with another joint project.

"We've got a whole bunch of songs, and we're just going, 'Does that work, and does that work?'" Plant tells the UK's Absolute Radio. "So we're trying it out again."

Working on new music, the two know they have a tough act to follow. 'Raising Sand' landed five Grammy nominations, including Album of the Year. Their tour supporting the album sold out in cities across the country, and sales of the CD have topped one million.

"The critical stuff that we've had, the acclaim, it doesn't bode very well for the next record if we get that far, because people really took to it," says Plant. "It was so genuine -- the choice of songs, the production techniques, the engineering ... The whole thing was just a dream. Of course, you don't expect anything because the material isn't kind of mainstream pop particularly. So yes, a real blast, but we have laughed our way around the planet, which is quite special."

So what will the duet partners title their sophomore collaboration? That's a work in progress.

"Last night's title for the next project was called 'A Gated Community,' because it's like being in a looney bin," Plant jokes.