Since then they've graced stages at Coachella and SXSW, and accumulated over half a billion streams globally.
The pair share why winter can be the best time to visit, the natural attraction every tourist should see and what sets the country apart from the rest of the world.
You've travelled the world while touring but what makes Australia so unique?
For how expansive the country is, and how far apart all our major cities are, there's something equally incredible about the diverse individual character of each city.
For example, Sydney. There are not too many other cities or even countries where you can swim in crystal clear water while staring directly at the CBD.
What Aussie destinations are at the top of your travel list?
We'd love to go see the Pink Lakes in South Australia and return to Uluru and Kata Tjuta.
It's so easy to ignore the famous holiday destinations that lay on our doorstep, because of how often we're exposed to that imagery growing up here. But there's nothing that compares to seeing these locations in person.
Having seen Uluru thousands of times in books, and on television, nothing did it the justice of seeing it up close. We can't recommend it highly enough.
What is your most memorable Australian holiday?
As a child one of my most memorable Australian holidays was to Heron Island on the Great Barrier Reef. It's one thing to fly over it, but it's another entirely to stay on it.
Seeing turtles lay their eggs on the beach at sunrise, and being able to snorkel off the edge of the island at any point, to find yourself amongst tropical fish and brightly coloured coral is an unforgettable experience.
Are you planning any side trips or experiences while on the road in Australia next year?
Hopefully we'll get a little bit of time in each city to explore. We're pretty familiar with the central parts of each Australian city now, so the really special experiences are getting further outside them.
Getting down to Margaret River from Perth, or taking the Great Ocean Road from Melbourne have become almost regular occurrences when we perform more rural festivals. Recently we got to see Merimbula again, on the south coast of NSW. There are so many beautiful hidden gems down that way, it's worth taking the coastal road and finding a few for yourself.
Are there any particular Aussie destinations, or types of holidays that inspire your creativity?
As much as Australia is associated with the summer experience, the long drive to the snow in winter is a great way to get familiar with some new music and be inspired by the Australian landscape.
Leaving from Sydney, we get to pass Botany Bay, travel over the flat plains of Lake George, through the capital, over hills, before descending into an enormous beautiful lake in Jindabyne. To top it off, listening to music while skiing within eyesight of Kosciusko is never a bad way to get inspiration.
What are your top tips for international travellers visiting Australia?
It's inevitable that travellers will see what Australian cities have to offer. And it's easy to lose yourselves in the fun and excitement of those hubs.
But getting a car, and skirting the Australian coastline is something even locals should feel compelled to do at some point.
Our best travel experiences have been through unexpected discoveries. Drive up or down the coast, and poke your head out to a beach at random. You'll have the personal satisfaction of finding a small slice of paradise, and the strike rate for achieving that is ridiculously high. We still do this, and it never gets any less impressive.
