04 Z4 no sound from rear speakers

[dbarton62]

I have the business radio in my 3.0 convertible
When I bought the car the amp was missing so I bought a new factory unit from a well known online supplier.
The unit is the correct one for my car but there is no sound from the rear speakers only the front.The fade is set in the middle and all other functions operate as intended.
This may sound stupid but would having the ECU removed(it is out getting flashed for the S/C)
have anything to do with it. Can anyone shed light on this please.

Thanks
Dave

[Unregistered]

Ok no feedback on that post.I will approach from a different angle.

I have a stock BMW audio package with the ten speakers and a HU that has the musical note button that has Bass,Treble,Fade,Balance and Tone Lin? functions.......no DSP shows up on that function button.
I have a pin type connection in the trunk taped into the amp harness that I believe is what people are referring to as a coaxial plug.
1) Is my radio considered DSP
2) If it is do I need the "top" hi fi amp to run the 10 speakers.I bought a hi fi amp that has only the printouts for the big black plug.
3) Would BMW put the coaxial plug in all their harnesses even if a particular car might not be ordered with the DSP option.
4) Does the fact that the amp I have *not having an input for the coaxial have any bearing on the rear speakers having no sound.
This last one is the kicker
5) If the answer to #4 is yes and I do need a top hi fi amp does anyone have a good working amp to sell me or trade straight up for a brand new hi fi amp


Thanks*

Dave