Hi and welcome to Beoworld. 
Assuming the Harman Kardon FL 8380 CD player has RCA/Phono outputs it should plug straight into the CD input of the beomaster 5500. If you look at the inputs of the beomaster you will see that below the 5 pin DIN socket there are also RCA/Phono sockets which were intended for exactly this type of application.
Oh - unless the CD player has its own remote you won't have remote control function via the beomaster.
Chris.
EDIT :- I've just googled your CD player model and all you need is a male to male RCA/phono plug lead from the audio output of the CD player to the CD inputs as described above. BTW the beomaster 5500 is a nice amp.
The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.