Airfoil for Mac 4.5 from Rogue Amoeba allows you to send audio to just about any location in your house, using your existing network. You can make Airfoil connections to other Macs, PCs, Airfoil/AirPlay-aware speakers and components, Apple TV, and AirPort Express, as well as iOS devices. Even better, Airfoil will keep all of the devices playing in sync; you won't hear time-shifted audio playback from various devices as you walk around the house.
Airfoil for Mac 4.5
You're not limited to iTunes as the source of the audio. If you can play it on your Mac, you can stream it by Airfoil. You can also use any of your iOS devices as an audio source.
Airfoil for Mac is one of the best applications for Apple's Airplay technology. If you have a household you want to fill with music, Airfoil may just be the application you need.
Airfoil for Mac is $25.00. A demo is available.
See other software choices from Tom's Mac Software Picks.