I'm sorry to dig up an old thread but this is exactly what I'm wanting to do. I was originally running a quad core android based head unit but the audio quality was abysmal due to a poor DAC. So I've since switched out to the Pioneer 7100NEX. What I'd like to do is setup something exactly like what you have expect possibly using something like a MK808, My goal is to run Torque and be able to control it from the head unit. How EXACTLY did you set this up?