From what I remember about your goals for multi zone I think you should look into individual networked computers for each location, with a NAS device serving your media. Either ARM based ones like panda / beagle boards, or check out an apple TV. I just picked one up, and it's an amazing little box. Jailbreak done, now it runs XBMC perfectly and can play from any source, be totally customized, etc. One question, are people going to fight for audio control, or is each location intended to wear headphones? The Apple tv also would have the advantage of each passenger being able to just airplay off their ipad / iphone whatever media they carry or games in the near future.