Need advise in setting up streaming to different rooms on different systems

[Captain]

I want to stream music in more rooms from the same source.

At this moment I can play music in

 

• my study using a Mac mini streaming from iTunes library on this computer.
  
• My living room using a Mac mini streaming from a separate iTunes library. This computer uses Pure Music for up sampling. Than through a Musical Fidelity V-Link 192 to my NAD c390DD amp.
  
• Then I have a Denon DVD Home Entertainment System that has a network connection.
  

 

 

I would like to use these three systems in different rooms playing their own music. Preferably I would like to choose the music from my library using one or more iPads .

 

 

Question:

How do I set this up?

Do I need a NAS?

Will the Denon fit in this system?