IMPORTANT UPDATE: I now love Maroon 5.

I may be the last person in the world to do this, but I'm doing it: Jumping on the Maroon 5 bandwagon. Why didn't I notice their awesomeness before? His voice is so smooth. It's unreal. It has this relaxed quality. The only way I can think of to explain "relaxed voice" is to provide an example of the opposite: Katy Perry. She can sing, but you can always tell that she's working hard at it. You can sense effort, and good God, the melody just casually flows out of Adam  Levine's mouth. I wouldn't be surprised if he sings that way all the time, whether he's in concert, or hanging upsidedown on a jungle gym.