Theres a few head units on the market with built-in pre outs for multiple speaker set ups, (most commonly used in show vehicles that are all speakers). Stop by any audio dealer/installer and they can point you in the right direction. If you have a cabinet next to your system, you could also install an amp with multiple outs, and multiple device inputs to run hdmi, android and iPod docks. +2 on the a/b or a/b/c switch if you want it plain and simlpe, (cheap).
Days Camped 2011 - 52
Days Camped 2012 - 93