If I connect BS9000 with BeoPort/PC is it possible to play CDs from BS9000 via the PC loudspeaker?

I know it is possible to play mp3 files from the PC via BS 9000 via N.MUSIC function but I don't know if opposit goes to.

The short answer is YES

The long answer is the speakers need to be connected to the Beoport, either using seperate powerlink speakers or using the headphones output on the Beoport to feed into your sound card for the PC speakers if they are integrated etc.