Hi Paul,
Welcome to BeoWorld! Based on your description, it sounds like you have a Beolink Passive or ML/MCL Converter. The only cable you'll need between the BS9000 and the amp, is what is commonly referred to as a "fully wired" Powerlink cable. This is needed, as the BS9000 sends a signal through the Powerlink cable to turn the amp on, when the BS9000 is switched on. Other than that, you'll just need speaker cables to go from your amp to whichever speakers you are using. The Masterlink cable is not needed. You can do another type of connection with the Masterlink cable, but it is simpler to use the Powerlink cable, unless your placing the amp and speakers in a different room, than the BS9000. Hope this helps!
Tommy