Hi I am the proud new owner of a 2008 Mellow Yellow R56 with the factory "HiFi" amplifier and speakers installed.

It has a strange problem, there is a background white noise / hiss from the speakers on any audio input selection.

I have been able to remove the amplifier from the boot and directly connect the input to the output by making some jumpers from paper clips. The speakers were clipped at certain frequencies depending on the speaker output I selected, but I expected this, there are all component speakers. However the white noise was still emitted. This eliminated the amplifier as the source of the noise. It must come from the head unit.

In the audio setup menu, the gong setting emits a very strange massively loud machine gun noise when turned up "+3" and beyond.
I have to turn the whole car off to stop it. When restarting the machine gun is gone.

The white noise is there regardless of whether the engine is on or not.

You can hear the radio eventually over the white noise, but only after turning the sound up heavily.

On my experiment to eliminate the amplifier as a problem, I think I may have somehow touched one of the stereo output connection (+ and -)
together. The speakers emitted a short version of the machine gun noise, then stopped. After this the stereo worked normally and I thought my problems were over. I announced proudly to my wife "I fixed it", and packed everything away. When parking the car for some reason curiosity got the better of me and I had to see if the gong sound setting was fixed as well. Of course when I took it up past "+3", the machine gun noise went on again. White noise returned when I started the radio again. Expletives were emitted!

Have any of you good people out there heard of a similar problem and how to fix it?