Doppler affect caused by you driving away from the radio signal or CD sound
Sorry. My Mother has told me time and time again that smart-ass isn't cute.
Common factor for both problems may be power supply to the rear for the radio antenna booster and the changer.
I don't have a Bentley handy, but I'd suggest they both run off the same supply and this could be compromised by a bad connection in either a fuse box or wiring loom.
I'll check the diagrams later tonight and see what I can work out.