So this is a common old topic and for the most part I use a 1/8" audio jack from my WS-420 as the solution in my boat. I have come to accept the wired solution in the boating application.
Now in my new home I want to broadcast the music from my media room to the backyard, the master bedroom and my living room when we have a little get together at the house. Likely the solution will be an RF based solution since it seems Bluetooth is limited to a one to one connection. I need one to many. I like the way the Sonos system works with the iphone application but I don't really want to be limited to the Sonos powered speakers and amps. Brookstone has some fairly powerful speaker orb's that would do a decent job of reinforcing the music around the house in the living room and master but I believe they will fall short making the level of music I want in the backyard around the pool. My backyard is about 1/2 acre and I would like the music to be heard around about half of that area surrounding the pool that I will be putting in this winter/spring.
The architecture of the system would ideally take a bluetooth signal from my iphone to my media room receiver (Sony STR DN-1030), then split out to 3 RF transmitters to 1 RF receiver feeding 4 speakers in the backyard, 1 RF stand alone speaker in the living room, 1 RF speaker in the master.
Does anybody have any experience or recommendation for something that can do this or a better solution that I may not be aware of?