Hi Have the HU standing in the signature in the car, is that normal that adapts to the driving speed with the loudness? So I drive on the highway so at 110Km/h then the loudness has become higher, but the volume number has remained the same, and when I drive back into the city then without changing the volume number the loudness is quieter, that has already been noticed by all friends, so no imagination on my part, is that normal??? or is that a next-door Does the power supply??? or whatever? I hope someone can help me.