I've just been out in the S6 & was driving across a field, suddenly over a bump I heard what can be described as a "boing" type of knock noise, went over another bump, the same again. Didn't hear it again all the way home until I got back to my road when I heard it again . I jacked up the front of the car, had a good look around the suspension & can't seen anything obvious, did both sides & dropped it back down. As soon as I sat back in the drivers seat I heard it again, took it down the road & could hear it quite loud over certain bumps. My first thoughts were a broken spring or something with the anti roll bar but can't see anything broken or snapped. Any ideas what it could be?