Mixing and matching manufacturer's equipment is very difficult, and requires modification to the cable between the head unit and the changer (especially since most of the time the adapters are proprietary and don't just plug and play).
Yeah, I'm somewhat obsessed with head units and audio sources in particular. :P At one point I had 40+ unique decks simultaneously. I've tried mixing and matching all kinds of parts such as ribbon cables, CD mechs, changers, faceplates etc. Sometimes it works; most of the time it doesn't. It's difficult to say the least.