Soundsystem

We'll use the Creative Inspire T3130 2.1 Sound system, which we picked up used for 25€.  The whole set is 25w total, with 5w each satellite and 15W for the sub itself. Should be powerful enough.
The volume control's on a cord, so it can be placed outside of the cab which is pretty convinient.

Creative Inspire T3130

We decided to take the legs off the subwoofer and put it on foam rubber to decouple the vibrations from the cab. We cut aluminium angles for the frame and put felt on it.