I have a 2001 330xi with the upgraded Harman-Kardon system and in-dash CD player (no CD changer).
I installed a Blitzsafe auxiliary input adapter in the car by attaching it to the CD-changer hookup in the left side of the trunk. I have run connectors up to the front of the car so I can hook up both an XM satellite receiver (Delphi SkyFi) and an MP3 player (Rio Karma).
Both work great and I can play the music through the stereo just fine, but there is a buzzing sound in the background that I can hear if the volume is up high or if there is a quiet spot in the music. I know it is not the stereo itself, because the buzzing goes away when I disconnect the Blitzsafe adapter. It is not the specific Blitzsafe adapter either, because I just switched from an older original Blitzsafe auxiliary adapter to a different new Blitzsafe adapter that allows you to hook up and power the Terk XM Commander. The noise DOES NOT vary with engine RPM.
Has anyone else had this problem? What can I do to make the sound cleaner?