Media Reciever Change?

Here's the details:

Year: 2007
What is got: touch screen controlling heat and audio that's it.
Media Reciever: CD only (no aux input)

Now on to the question: am i able to get an after market reciever (i.e. pioneer media reciever) and put that in, instead of the factory which it currently has, or will that break the touch screen's functionality? Please try and speak gentle cause i don't know cars very well..and if i can't change the factory cd reciever then i will have to find something else. Thanks for any insight!