I haven't noticed any vibration and the milling sound is quite loud in my car. I'm booked for a drive unit replacement in mid May. The milling noise is heard with any amount of power at low speed, and it increases in frequency with speed. It's most noticeable in a parking garage with your windows open, but you can hear it any time. At very low speeds, it sounds more like a growl/purr, and then as you speed up it sounds like an electrical whine/buzz, and as you pass about 40 km/h, the frequency of the milling noise goes up to hearing limits and it gets lost in the wind and tire noise.