Alison Krauss thinks Dolly Parton is ''so naturally perfect''.

The 'Windy City' singer gushed about collaborating with the '9 To 5' hitmaker but admits it can be a bit of a ''Pandora's box'' trying to match her flawless harmonies.

She said: ''I adore the process of it, it's like trying to get inside someone else's head. Like Dolly Parton, who sounds like it's just the easiest thing in the world for her to sing something and it's so naturally perfect.

''And then when you go and try and sing harmony with her, it's like a Pandora's box, nobody else does it like that. And you think, how in the world can I match it? And then the times you sing with somebody else and the more times you don't match them, the more romantic it gets.''

And Alison enjoys being able to collaborate with different music artists and describes the whole experience as very intimate but a ''fascinating process''.

Asked if collaborations are intimate, Alison told NPR's Morning Edition: ''And when you have headphones on and when you can hear every click of their teeth coming together, spit flying out of their mouth, it's quite ... amazing. It's a fascinating process; I love it.''

Meanwhile, Alison is gearing up to release her first album in 17 years, which she says has a tinge of sadness but not in a ''pitiful'' way.

Alison explained: ''It's almost like you didn't know it was sad because it doesn't sound weak. It doesn't have a pitiful part to it, where so many sad songs do.

''But these don't. And I love that about it. I love that there's strength underneath there. That whatever those stories are, they didn't destroy. That that person made it right through it. I love that.''