It is a different function. The d50 is a dac and the CCA is a streamer with inbuilt dac. That Dac is good but not perfect. With your speakers you will probably not hear the difference. But if you want you can use the CCA as a digital source (it not only has an analogue output that uses the internal dac but also an optical digital one that bypasses the inbuilt dac.). This may sound marginally better.
I can't tell the difference between the analog outs on the CCA and the dx3 using those audioengine's.