Bmw m3 e46 harman kardon help!

[kiman]

Hi.

Where do I find the harman kardon amplifier on my BMW M3 E46 -05 ?

I´m having trouble with the subwoofer. When the car stands still it works perfectly but when I start driving it glitches and sounds really bad. I dont know why this is happening. Sometimes it can work perfectly even when Im driving but the last couple of days it has been working really bad. Anybody else that had this problem? I have harman kardon audiosystem on my car so I was gonna start searching on the amplifier. It´s only the subwoofers that are glitching and making bad noise when the car starts moving. I sent the car to BMW but they didnt have any answer. Could it be the radiomodul ?