Is the 6-disc CD-changer that goes in the glove box the same unit that has been used for the last couple of years in the C-class ? Since the sound system for 2005 is a Harmon-Kardon unit of better specifications than the old Becker unit I wondered if the CD-changer has been similarly upgraded as well.

The CD changer is still a unit built by Alpine for MBZ. This one for '05 is the same as previous years, but now the factory is saying that it can no longer be added at the dealership level. They are not telling us that the CD changer has to be factory installed and you cannot put it in after-the-fact. That is the only update to the CD changer for MY05 to my knowledge.

I think there is some difference in the electronics in the CD changer, beucase some the CD's that used to work before on my 01 C240 dont work on the new one. They did not have problem on 330CI h/k system. I am thinking it is either the unit is having problem playing it back or may be th electronics on the CD has changed.

So don't most of the aftermarket Alpine units play MP3's now? Why doesn't the OE unit in these cars do that? Or can we change to the aftermarket one (maybe with a bus adapter) & pick up that ability?

My C55 audio is called Audio System 2 . It is better than '1'
But Harmon-Kardon is an upgrade option.

For MY '05 the optional CD changer and the optional telephone communicate digital information, including the music, to the stereo, along the MOST fiber optical ring.