Need advice on digital inputs

Looking for a little advice on something...still a bit new to all of this. I have an NAD c379 preamp and a Cambridge audio cxn100 streamer. I have the Cambridge hooked up to the NAD from the analog outs on the Cambridge to the analog ins of the NAD. Both of these units have good dacs, so having it hooked up like this which dac am I using, the Cambridge or the NAD?? The Cambridge has digital inputs and outputs, the NAD only has digital inputs, how do I use these on the Cambridge unit? Thank you for all and any advice.