the only one in the appstore!

Very good project, it works with every airplay speakers.. I personally use it with two airport express and one apple tv and its pretty good and easy to use..
Sonos multiroom system, thanks to Sonos app is another world but if what you need is a useful app (now works even with deezer) at low price, this is what youre looking for.

trasathebest about WHAALE Multiroom Player, v1.5.3