Watch Adam Levine and Gwen Stefani Bring Ballad 'My Heart Is Open' to 2015 Grammys

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Gwen Stefani and Adam Levine perform on stage at the 57th Annual Grammy Awards in Los Angeles on Feb. 8, 2015. 

It was time for a lover's ballad at the 2015 Grammys, and the sharply-dressed pair of Maroon 5's Adam Levine and Gwen Stefani fit the bill. Their familiar voices combined for a performance of the stripped-down piano ballad "My Heart Is Open," off Maroon 5's 2014 album V.

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The pair of Voice coaches performed in classic evening attire in front of a string-laced, orchestral backing, ready to let those feelings out. As the bows flared behind them, Levine and Stefani let their voices go to work.

It wasn't Maroon 5's usual funk-pop and it's a far cry from No Doubt's rock; what do you think of their grown up vibes? Who's voice dominated the duet?