i know this an old thread but I wanted to get some advice.
I also have xbmc on my iPad 3 successfully streaming content to my tv via hdmi.
What i've been trying to find out is whether I can output audio to my bose airplay speakers.
Now the thing is, I know its somewhat possible, because yesterday i managed to get it working by chance. In this order, I was airplaying youtube vids, then i opened up a game ( asphalt 8) and noticed that the game sounds were coming through my Bose speaker via airplay

so I thought hey.. let me try and stream a movie from XBMC, and low and behold it worked!

I was getting the audio over my bose... side note, the audio was out of sync but using the audio options in xbmc i offset the sound about 2sec on this particular movie and worked out perfect.
Now my question is, was this a fluke or is this genuinely workable just not fully supported, as all my research up to now and on the official xbmc forum points to this not be possible. I know its suppose to work in the reverse, as in airplay to xbmc but not vice versa.
also shame to hear the quality lacks in lightning connector on iPad 4! I was looking to upgrade to the upcoming iPad 5 once there is a JB out for it, but this news has me concerned.