Originally Posted by blkxer

I think this is what you're looking for; it's for the E39, but should be the same for the E53. Take note that with the workaround, you won't be able to use the volume control on the head unit and will have to use the volume controls on the steering wheel (if I understand it correctly)

E39 DSP workaround with Hualingan - Bimmerforums - The Ultimate BMW Forum