In most cases you will need a network of some type, be it hard wired or wireless. Amazon has thought this out as well with their video series Networking 101. Once your network is up and running, they have broken whole home music into three options.
Option One - Whole-Home Systems
Whole-home systems transmit audio from a central location (such as your computer) to a plethora of amplified possibilities: a home theater stereo, powered speakers, an HDTV, and more. The audio that is being served up through your home can either be the digital audio files stored on your computer's hard drive or audio streamed from an Internet radio station.
> Shop whole-home systems
Option Two - Wi-Fi Radios
Wi-Fi radios stream content from Internet radio stations, which requires an Internet connection. As the name suggests, a Wi-Fi radio can wirelessly connect to the Internet (the source) over your home's wireless network router (the transmitter), and it acts as the direct receiver. It doesn't require connection to your computer, only to your network router.
While Wi-Fi radios don't require a connection to your computer, some offer the capability of streaming stored digital audio files (such as MP3s) from your computer's hard drive. Also, some Wi-Fi radios offer a wired Ethernet option as a feature.
> Shop Wi-Fi radio's
Option Three - iPod Streaming Solutions
Apple iPod-centric solutions provide an easy way for you to stream music from your iPod or iPhone to wireless speakers or receivers throughout your home. Many iPod streaming products can operate independently of a home network, so if that's an option you're interested in, be sure and read more on product detail pages.
> Shop IPod Streaming solutions
Apple Airport Express
The Apple Airport Express is a compact wireless base station that acts as a receiver to audio transmitted over Wi-Fi from a computer music source running the Apple iTunes software. The Airport Express connects to an amplified speaker via an integrated 3.5mm audio jack output.
Music sharing is just one function of the Airport Express, which can also be used as a standalone Wi-Fi router (great using while traveling), extending the range of your main Wi-Fi router, or providing access to a printer (via its USB port) to a wireless network.
> Learn more about the Apple Airport Express