Loose ball hubs that don't have a spacer cage, like Shimano hubs, tend to make noise as the balls clack together. There is nothing you can do to fix it. Fresh grease helps but will quickly get pushed out from between the bearings and the noise will come back. This is not an adjustment issue nor a pitted bearing issue. Tightening the cones will help a little but if you tighten the cones too much, the bearings and races will be damaged. I say all this because I've spent a considerable amount to time trying to eliminate this type of noise on two different Dura Ace 7700 hub wheelsets, only to fail. Best to live with the noise.

As a side note, I've noticed that some frames tend to magnify these noises more than others. I have a Ti frame that rings from all the little vibrations/clicks/random noises possible. My steel frames on the other hand are much quieter.

Good luck.

Ed