Wireless music adapters send audio signals wirelessly from one device to another. For example, connect one adapter to the USB port on a computer and connect another adapter to a stereo system in another room and play iTunes music wirelessly through the stereo. Or set up a wireless multiroom system between the main stereo and stereo or tabletop systems in other rooms by using multiple adapters. All that's required is an audio output on the sending device and an audio input on the receiving device. Aperion Audio offers HAL (Home Audio Link), a simple and affordable system. HAL is also a great way to make a wireless subwoofer system and eliminate the cables running on the floor. HAL can send almost any audio content wirelessly between two or more rooms and is expandable to as many as three rooms with additional HAL receivers.
If you store your music on iTunes (and who doesn't?), check out the , which acts as a receiver for Apple's Airport wireless signals. It's compatible with Mac & PC (Macs have Airport built-in, but it's available for PC) and the Airport Express is also a wireless router when connected to the Internet. Read my full review of the Apple Airport Express.
Listen to Internet Radio, iTunes and other content on the Bose SoundLink, a multiple portable system you can take with you between rooms.