I don't know if is it possible, but this feature would be very nice.
DLNA works well, but i don't know if we can stream under dlna. And for that airplay works quite pretty.
This idea has been submitted more than 2 years ago but unfortunately hasn't gained enough kudos during that time (10 kudos/year). In order to keep an overview of the active ideas in this forum, this idea will be closed for now. Note that this does not mean the idea has been declined by Spotify.
Please feel free to re-post this idea if you still feel you want this implemented. With a little change in presentation, maybe this time it will gain the necessary support from the community.