I've been reading these threads about horrible bass in the Z4M Coupes, and it sounds exactly like my problem. I just purchased a 2007 M Coupe with premium sounds and navi, and although I haven't checked yet, I assumed the subs were blown as I get horribly distorted bass, even after adjusting the EQ and DSP. I used to have a 2008 M Roadster (prem sound no navi) and I thought that system was great--absolutely no comparison to what I have now.
It seems that all of you have found the problem, and I appreciate you documenting all of your efforts here! I do have a couple of (perhaps stupid noob) questions:
1. I'm not sure I feel comfortable re-programming the car myself, although the price of the cable/software wouldn't be an issue. Can I just take the file that pungo shared and have a local bmw shop use it to update my file?
2. I would like to update the navi maps and firmware using the
www.bmwnav.net software. Will this have any impact on the amp coding fix? I.e., should I do this before? after? not at all?
Appreciate any advice you can offer! I used to love blasting the stereo in my Roadster, but this new Coupe makes me want to just leave the system off....