A Harman Kardon subwoofer multi-media speaker system, model HK695-1
If you're hooked on the idea of wireless audio, but don't want to replace your perfectly capable wired speakers with the wireless kind, a digital media adapter may be the way to go.
PlanarMedia™ 14 Multi-Media Speaker System
A multi-zone control system is essentially a switch box (like the speaker switcher) that allows you to send a selected source (e.g. DVD, CD, turntable, media player, radio, mobile device, etc.) to specific room(s) in your home. These control systems can send either line-level signals to amplifier(s) located in select room(s), or they can feature built-in amplifiers that send speaker-level signals to the selected rooms(s). No matter which type, these control systems allow you to listen to different sources simultaneously in different zones.
Those fortunate enough to own a home with network wiring already installed throughout can enjoy a significant advantage. The same type of cables (CAT-5e) used to connect a computer network system can also distribute audio signals to multiple zones. This saves a great deal of work and time (as long as speakers have or can be equipped with the connection), because you don't have to worry about running wires (i.e. measuring lengths, drilling holes, etc.) all over.