The chamber still comes from the ground. It's just a path from ground to enemy that gets more muscles involved. As a white belt it's chamber - pause - kick. As a black belt you pass through the chamber in a smooth motion to kick.
Even a jumping kick, done properly, the power comes from the ground, because you're pushing off of the ground to give yourself the momentum you swing through.
If you do happen to pause the chamber*, I'd argue your power STILL comes from the ground, because the chamber is like a spring coiling from the initial motion to uncoil in the kick, and your other leg still presses on the ground to give it the power. You do lose momentum, and you do lose some of the energy in the kick, but the power is still coming from the ground.
*Reasons to pause the chamber include: faking (I've used a chamber as a sort of changeup-pitch to throw off the timing of blocks before), timing, reading your opponent as he responds to your leg moving, using the chamber to block a kick, and that's off the top of my head.