Q: Mac Pro wireless audio out to any speakers

Dear forum friends,

I've researched for a solution that will allow me to connect a set of Bose speakers to my Mac Pro wirelessly. I was looking at the AirPort Express but it seems it will only let me output music from itunes.

Is there a solution that will allow to play ANY sound out of a Mac Pro to a set of speakers wirelessly. I need to do this because I will place my Bose speaker set on a book case that's against a wall behind my desk and I don't want the cable running across the room.

I other words. This is a normal setup using 3.5 mm audio cable out of the Mac Pro into the speakers. I just want to get rid of the audio cable.

I also don't want to be restricted as to what application I can use. I want to be able to send any audio to the speakers such as Youtube, Pandora, Spotify etc.., and of course iTunes.

Thank you for any ideas!