I wonder if the cd players used in the various beosounds/centers are in fact the same; my beocenter 9300 has specifications that are exactly those of the beosound 9000 and beosound 3000/3200. Only beosound 4 and beocenter 2 are different; because they're newer/more recent? 

The reason I'd like to know is, that I think the sound of the CD player in the 9300 is not very good, violinconcertos sound somewhat stressed/harsh. There're is little dept or smoothness as compared to earlier players like beocenter 9500. (and yes I heard them through the same speakers)

I could imagine that the CD mechanism is the same in all, probably Philips?

But there is so much involved to a good CD player if it contains DAC's and isn't merely a transport (as I use my BS9000). Powersource, DAC's, mechanism etc... all make up the CD player. So I don't think they are all the same.

The Beosound 9000 is a much better CD player than my old Beocenter 2300. (Much newer as-well) 

The older Beocenters (9500/8500/9000/8000) all used the radial version of the CD transport (where the laser moves in an arc) and the rest of the circuitry is very similar between them, just like the Beogram CD5500-7000.

The 9300 is different. It has the later linear transport (early units had the radial one, though) and the rest of the CD player - and the entire system, actually - is technically much closer to the Beosound Ouverture than the earlier "flat" Beocenters. So it is quite probable that it sounds different as well.

The actual mechanisms changed fairly regularly. The sound quality will be more likely to be due to the DAC installed. The CDX uses a TDA1540 and the later 16 bit CD players used the TDA1541 - the basic ones use the normal TDA1541 whilst the top of the range use the TDA1541A and some even have the P version. These are still well thought of. If you find that the sound is dulling, it may be that some components are aging. Worth a service?

As the 9300 is younger than the 9500 I listened to, in this case aging isn't the problem I think. Therefore I would rather not sell the 9300, it's just looking like new. But the musicality of the CD player doesn't convince me, the radio-section sounds good so the difference in sound must be up to the CD section. About the DAC's; can you configure your own CD player by "simply" changing the DAC?