Watch: Kiwi Sibling Duo Stun Judges in Their X-Factor Australia Audition

A Kiwi brother and sister duo has wowed the judges on the Aussie talent show, playing an acoustic version of Major Lazer's hit Powerful.

Isla and Finley Brentwood - better known as Brentwood Duo - are originally from Queenstown but now live in Melbourne.

They're already a hit on YouTube and regularly play at pubs, corporate functions and weddings around Australia and New Zealand.

X-Factor judge Guy Sebastian was floored, describing their voices as "insane", while fellow judges Iggy Azalea and Adam Lambert both looked notably impressed.

How could you not be impressed with those flawless harmonies?! 

Brentwood Duo will appear on X Factor Australia when it returns to TV3 at 7pm on Sunday.