halid: For example, what is the difference between 1 and 3?
well as Phillipe says, "DRM songs cannot be played."
I never use LinkMusic ... but that's not for that reason, but rather because I subscribe to Last.FM, and LinkMusic does not interface with Last.FM whereas iTunes does -- so that is a plus for me.
I suspect Phillipe wrote the code for LinkMusic and LinkRadio because he wanted a light-weight piece of software ... which iTunes is not.
On the other hand I have used LinkVideo, but that is because it allows me to find Videos/TV Shows/Movies that my LinkPlayer PLEX set-up does not "find" (or perhaps does not recognise).
By the way, have you downloaded Phillippe's PDF with its Beo4 guide ? That has a few more differences -- I think it comes down to what we call "horses for courses" (in other words, it depends on what YOU want, which in Phillippe's case was light-weight S/W!)
First B&O (1976) was a Beogram 1500 ... latest (2011) change has been to couple the BL11 with the BL6Ks *sounds superb*