ok, so this means the Apple dock still relies on the iPod to decode and convert to analog signal.

On the other hand, the USB used by the Alpine and others must be different. I don't think you can send analog signal over USB, so this is consistent which what I am reading around: Alpine gets the bitstream out of the iPod and then converts it to analog signal. Do you think this makes sense? Back to what Tony was saying, I assume Alpine also decodes the signal, just because it would make more sense / be easier to do in my opinion...