Hi Christian.
If you want a good quality non B&O alternative to spin those old LP's then consider a Pro-ject Debut record deck with built in pre-amp.
Brand spanking new for less than £300 complete with cartridge and they get rave reviews.
It will plug straight into the aux input on the ouverture. I did exactly the same a few years ago and now have the same turntable plugged into my Beosound 4.
Pros : A good "out of the box" quality turntable without the worry over expensive B&O MMC stylus replacements.
Cons : No control via beolink and not the same wow factor as the classic tangential players.
Mine is in a sideboard below the Beosound out of view so I can live with it being non B&O!!
Only minor critisism is that even with the pre-amp, the relative volume is a bit lower than the CD or radio on the Beosound so some adjustment is needed on the volume control.