Thinking about buying one of these sliding door-systems (second hand), are there any arguments in favor of the 2300 or 3000? I read something about cheap plastics used, did these materials upgrade over time in the 3000? Any differences in sound or quality of the CD player used?

George

the 3000 has Masterlink-Connection, the 2300 only via Converter! 

The major advantage of the 3000 is that it has an ML connection and can work with N.Music in most cases. The early 2300s have two way communication. I don't think the quality of construction changed much though the DAC changes from a 16bit in the early 2300s to Bitstream. Some prefer the 16 bit devices for sound.