The 518 Gives 4 Digital Inputs into the 565. You also Have an Analog Input to the 565 which you can expand with the 562v.
With the comms leads this will give no problems as you will have the 565 as controler.
You set up the 518, D1 = CD, D2 = Dab Radio, D3 = DVD etc (You Choose)
You set the 565 to CD = Dig, DVD = Dig, Dab Radio = opt or analog etc again, you choose.
Match the Input and output word lenths.
Typicaly Input 16 bit, Output 24 Bit. It doesnt matter if you use Profesional or Consumer.
Study the 518 Manual as to emphasis setting and Dither. And there you go.

It is simple once you get into it.
I have 565 z36.2a and A 518 596 and it sounds Great.
Good Luck, Chris:)