The AC adapter shouldn't be making any noise at all. There isn't any motor inside to make any noise. It's just a bunch of electronic stuff that converts the current so that it's compatible with the 360. Are you sure it's the AC adapter and not the 360? I know the 360 makes quite a lot of noise due to the fan running.
Answers & Comments
Verified answer
The AC adapter shouldn't be making any noise at all. There isn't any motor inside to make any noise. It's just a bunch of electronic stuff that converts the current so that it's compatible with the 360. Are you sure it's the AC adapter and not the 360? I know the 360 makes quite a lot of noise due to the fan running.