I couldn't stand the sound from the Becker unit. 3 channel presets along with having a code for power failure. I tried replacing the stock speakers with good ones and it still sounded lousy. I was really disappointed in the quality of the stereo for an expensive vehicle.
I agree - the Becker Sound 30 leaves a lot to be desired. I have yet to be able to test this theory in practice (less time and money than my theory testing interest would like . . .), but from all the posts that I have seen sound quality can be improved as follows:
1. Better speakers in the dashboard
2. Better or added speakers in the rear of the van (I don't know about other Sprinters but the Westfalia comes with speakers in the ceiling above the kitchen)
3. Adding a self-powered or other sub-woofer (Westfalia installs them on the underside of the kitchen counter above the foot well of the lower bed - as a custom addition after purchase)
4. Replacing the head unit (Becker Sound 30) in the dash
The above are intended to be listed in order of cost/ difficulty from lowest to highest.