Which setup?

[NYC-Havok]

Sony-Mobile ES CDX-CA760X (head)
Sony-Mobile ES CDX-848X (changer)

or

Pioneer DEH-P730 (head)
Pioneer CDX-FM1277 (changer)

Also, you can cross brands right? i.e. There is no problem with hooking up either settting to (example) a Rockford Fosgate Amp speakers? Thanks!

[natem33]

For amps and speakers you can cross whatever name brands that you want. For changers and HU's, you have to use the same name brand CD changer as your HU.