Today, Runga is an independent artist enjoying the "new-found freedom" that has afforded her.
"I'm curious to know what can be done, because there is no protocol within the business that you can follow any more. It's all just anyone's guess on how to do this."
Runga has spent much of the past eight years focused on her two children and has a third on the way. For long periods she shut the door on music. "I concentrated on my family. They came first."
But then came a yearning to write songs again and, when she did, "It was like flying", she says. "I had to take this time out to really appreciate music again. And, you know, family life is really full on. Everyone needs something else as well, and I guess I was neglecting my own creativity for a long time.
"That's just what comes with motherhood. Now everything feels a bit more in balance. I see it [making music] more as a necessity. It's something I need to do for myself."
When she had half an album's worth of songs under her belt, Runga realised she needed to get out and play them. She approached Hollie Fullbrook, the singer-songwriter who fronts the band Tiny Ruins. She hadn't met Fullbrook but liked her music and asked her if she'd be keen to tour.
"I wanted to get the ball rolling but I don't think I could've done a tour on my own. Hollie has got quite a profile, and I'm a big fan of hers.
"I'd watched a lot of her interviews and live performances and I just knew that I'd really like her."
It's not a combination many would have picked. Runga, the doyenne of sweet Kiwi pop, and Fullbrook, the much younger voice of moody, melancholic folk. But ignore the pigeonholes and you have a beautiful musical partnership, evidenced by the mesmerising performance the pair gave in a recent session on Radio New Zealand.
"There is something about the textures of our voices that work well together and we have similar tastes so, aesthetically, we're kind of coming from the same place.
"Hollie is unique. Commercial music is so amped up, full on and loud and she's so different to everything that's big at the moment."
Runga's band and the Tiny Ruins hit the road this week, starting their nationwide tour at the Mayfair Theatre in Dunedin (June 25) and ending at the Civic in Auckland in early July, with a show that has sold out so quickly promoters have already added a second to the billing.
The performances will open with a Tiny Ruins set, followed by an intermission then Runga's set. The final part of the show has both artists and bands on stage together.
"The rehearsals are feeling great. It has really come together in the last few weeks. There has been a lot to learn in the way of each other's songs and covers. But it's all starting to gel now," says Runga.
There is no doubt the healthy ticket sales to date are a great pleasure to Runga, who admits it is daunting to return to a landscape that bears no resemblance to the one she left. She refers to a critical point in the music business last year when, for the first time, digital sales surpassed physical ones. She also points to the soaring rate at which audiences are signing up to streaming services like Spotify. And, of course, there's the newly revealed Apple service, which looks certain to be yet another game-changer in the industry.
"I feel like I actually sat out the most tumultuous part of the record industry's change. In that time I was watching everything happening and didn't understand what was coming but now it seems quite clear what's going on and it's perfectly fine to be independent," she says.
"The thought of being from New Zealand and being able to just concentrate on online matters more than having to have a big global label behind you is exciting."
There is a flipside, however.
"I don't know how people in the music business are going to keep employing staff, or paying themselves. It's going to be so difficult now with artists getting less and less [from streaming]."
But, as Runga sees it, there is a clear answer to that dilemma.
"It's not about money anymore. It has to be about good taste and good product."
It's why she's taking her time with her new songs, and why she's so pleased that the upcoming tour with Tiny Ruins will give her the chance to unveil some of them, including the single I Dreamed A Dream, which comes out as a digital release on Friday, June 26.
It's a sweet Simon and Garfunkel-esque song, with a woozy 70s vibe that peaks with a psychedelic, disco instrumental under soaring harmonies. Runga's voice is vulnerable and yet she has lost none of that haunting power.
She hopes the new album will be out early next year but, with her third child due in September and given the aforementioned changes in the way we now listen to music, she's taking a different tack with this record - similar to the one she used on her breakthrough 1997 record, Drive.
"We didn't make a full album all in one go. We made the first single, Drive, and that went well so we kind of did more. So I think I am approaching this record like that.
"It's such a singles market now. It's all about one song. You just have to put everything into that. People do still buy albums but I'm just trying to think about each song as the most important thing on my plate at any one time."
With no major label pumping in money, there will be no bells and whistles. But that suits Runga just fine.
"We've come to the realisation that maybe you don't even need a music video. They used to cost hundreds and thousands of dollars back in the 1990s and I'm sure some big artists are still spending that kind of money on them. But you just can't do that anymore.
"And anyway, people's eyes are more in tune with a different style of photography now. Things don't necessarily have to be slick anymore. There are people making it on their terms, with DIY stuff. It's incredibly exciting."
It is a different game now. But many of her goals have changed just as much as the playing field.
It is almost a certainty that her new music won't sell the way her earlier material did.
But even after years absent, there is a good reason why she still rates as one of the country's most respected singer-songwriters.
The word is talent.
