I think LMCE can be a candidate. I use this for playing the same song in all rooms, or different songs in different rooms.
All that would be required is to have a Media Director (MD) in each of the rooms you wish to have sound. These can be connected to TV's or to stereo systems. LMCE controls things through pipes. You set these up in the connection manager. In my home I have a core/hybrid in the living room or theater room. I also have a MD in the family room, and in each of the bedrooms. Now the core system, runs it all. Every other computer in the house is hooked up to a TV. To play movies/videos in the living room, it naturally uses my AV Theater receiver. In each of the other rooms, it uses the TV speakers.
Now because of the pipes I have set up, the theater room volume is controlled via the AV receiver. In each of the other rooms the sound volume is controlled by the TV speakers. This will most likely be the default setting, but by using the connection manager (example of my living room here http://dataless.jeromenet.org/lmce-stuff/connmangr.PNG
my video output from the lmce is connected to the TV, the audio output from the lmce is connected to the AV Receiver.
Unlike my MD's which have both the video and audio output of the lmce connected to the TV's.
If you decide to use computer speakers or whatever for your other rooms, a pipe will need to be connected to the amplifier if you use a stereo system, however if you use PC speakers, no pipe is required. LMCE will automatically control the PC sound.
In my situation, I can fire off the same music to all MD's at once, or individually. But each room has its own volume control, so it can be adjusted locally.
I hope this helps a bit. I know LMCE can handle multi-room audio, and video, and a host of other things. Most of the individual controls can be configured with the connection manager, however, using an orbiter on any of the MD's or the main system, or your phone or laptop, you can from a single location control the volume in any room. This helps when my daughter is blasting her audio in her bedroom, and I don't want to hear it in the other parts of the house, I just call up her room on any orbiter, and turn it down myself
You will find that LMCE is the most advanced, and heck, the coolest system you will every install, and although daunting at first, can be configured quite easily.