I just got an 04 roadster.
I love the car, but I'm having an issue with the left front speaker cutting in and out. It seems random, I will hit a bump and it goes out, then a few seconds later it may come back, or 10 minutes later it may come back.
The odd part, it is passing low frequencies when it cuts out, if i set the fade and balance to front left, I can still hear the low frequencies.
What should I do?

 

I have the same problem in my 04 with the Bose system when listening only to CDs.
It's a known issue, there are a few threads on this topic.
Replacing the radio appears to be the only fix.