I know some of the US people have replaced the factory head unit on the new C class with a European In-Dash CD Audio 10 (BE4410 / BE6021). I am tempted to do the same, not because of the in-dash CD (although that is welcome), but because of the availability of an aux-in (Audio 10 BE6020) add-on for that unit. Many here state that there is some improvement in sound, but I would like to dig further into that as it seems improbable.<br> <br> The US stock system is an Audio 30. The In-Dash CD is an Audio 10. Every place in the world where both are available, there is a US$ 400 to 500 premium to go from Audio 10 to Audio 30. Purchase price of an Audio 30 is twice that of an Audio 10 at MB parts stores. Audio 30 is rated at 25watts x 4, whereas the Audio 10 is 15 watts x 4. All seems to indicate that the Audio 30 is the higher-end, supposed-to-sound-better unit (designed to handle telephone and changer). For those of you have changed the head unit, can please indicate whether you see a difference in sound quality, and it what direction? Please also indicate whether you have a sedan/coupe and Bose/non-Bose. Please note that the sound quality, in order to be compared fairly, must be from the same source (e.g., in dash CD vs a CD in the changer, or FM station vs FM station). I would very much appreciate your statement, as I'm in the process of making a purchase decision shortly.<br> <br> Thanks.