All I have is treble no main speakers

[AndyB6T]

Hi everyone. Ive just bought a B6 2007 TDI S model so the normal CD unit package.

Beautiful drive. I had a Golf GT TDI DSG a few years ago and knew that one day I would return to VW.

Ok so....

My sound system works but only the treble speakers are working. It looks like a decent system to me and probably quite loud if my bass low frequency exisited in the first place. I suspect the following but obviously my experience is limited. Possible causes:

Amp gone to heaven.
fuse.
head unit failure.
All main speakers gone. (unlikely)
Loose connection.

I suppose my main question here is which one is it more likely to be? Is this a known fault ??

Any help from you lovely fellow owners would be grand.

Thanks in advance.

Admin, I apologise if this should be in ICE section.