Help, do I need a pre-amp?

I have a Cambridge Audio 851N network player with built-in preamp. And a Cambridge Audio 851W power amp. These two are connected with RCAs currently and are working great.

Now I have the opportunity to pick up a matching 851C CD player, which also has a built-in preamp like the 851N.
I want to hook this up to the power amp too

But … there's only one input on the power amp and how do I choose sources?

How would you hook this up?

Should I hook the Cd player to the network player?
Should I get a separate pre-amp and hook the two sources up to that and then output to the power amp?

Please help.

 

Simplest and cheapest is a switch box to select which source goes to the power amp. There are any number on Amazon for around £15. I have two, and they work perfectly.
S