(FORTUNE Magazine) – AS A MUSIC LOVER, I once enjoyed a whole-house stereo system that let me listen to my favorite tunes in the kitchen, the bathroom, or the bedroom, even though the stereo itself was in the living room. Of course, that was before I moved out of my one-room studio apartment and into a real house. Having more than one room complicates the musical ecosystem.

Until recently, only the super-rich could afford to install custom whole-house music systems. The fanciest of these systems use speakers and wires embedded in the walls and complex control pads that can separate the mansion into musical zones, allowing the owner to play Vivaldi in the formal dining room, for example, while guests in the drawing room are serenaded with Sarah Vaughan as they relax with brandy and cigars.

But thanks to the new Sonos Digital Music System, even the merely rich can indulge in the same kind of sensory extravagance enjoyed by billionaires (or people in studio apartments). Although it's not cheap--$1,199 and up, depending on how many rooms are added--the Sonos system outperforms many custom sound systems costing thousands of dollars more.

The Linux-based Sonos system consists of two or more shoebox-sized ZonePlayer amplifiers, one or more handheld Sonos Controllers, and your own stereo speakers. Using the iPod-like jog wheel and color display screen on the controller, you can stroll from room to room choosing albums or artists, switching among playlists, Internet radio stations, and music libraries, muting, pausing, and changing volume, linking or separating zones, and otherwise having fingertip control of your entire music universe. The music can follow you to any room equipped with a ZonePlayer receiver and, because the ZonePlayer creates its own wireless network, even to the swimming pool or garage. Or different family members can choose to play Green Day in one room, Maroon 5 in the next, Pink Floyd in the basement ... well, you get the idea. In other words, the Sonos Digital Music System takes the old-fashioned home stereo into the 21st century. The only drawback is that it may take until the 22nd century to pay off your credit card, especially if you live in a big house. Each ZonePlayer costs $499, and each controller costs $399, although you can save about $200 by buying a bundle consisting of two ZonePlayers and one Controller for $1,199 through the company's website (www.sonos.com). Each additional room you add to the network will cost $499 extra, plus the cost of any speakers and extra controllers you might want to scatter around the house.

I've been testing the new Sonos Digital Music System in three rooms, using three ZonePlayers and one Controller, for a total cost of $1,698, not counting the speakers. (Sonos plans to offer its own line of bookshelf speakers later this year at $149 a pair.) There are definitely cheaper ways to pump music over a home network into different rooms--I've tried the Roku SoundBridge Network Music Player and Apple's Airport Express, among others--but I haven't found any as easy to set up or as elegant to use as the Sonos system.

It took less than 30 minutes to have music playing in all three rooms, and that included 15 minutes on the phone with a Sonos support technician who patiently tracked down a glitch in my existing home network.

Although you don't need to have a home network installed to use the Sonos system, you do need to have a broadband Internet connection leading to a Windows 2000, XP, or Apple OS X computer through a device called a router. The router is not the same thing as a cable or DSL modem; it's a box that allows two or more computers to share one broadband Internet connection. If you don't already have a router, you can find good ones at most electronics stores for $50 to $100.

I plugged the first ZonePlayer into a Linksys Ethernet router that sits between my PC and my cable modem. Then, using the software that comes with the Sonos system, I took just a couple of minutes to turn on the PC's file-sharing capabilities and to add my MusicMatch and Windows Media Player music libraries to the Sonos index. (Later I did the same using a Macintosh and iTunes.)

While the first ZonePlayer communicates with the PC through the router, the other ZonePlayers and controllers create their own "mesh" wireless network that works independently of any wireless network you may already have. Adding additional ZonePlayers to the network is basically a one-button process. The drawback is that each ZonePlayer has to be within 100 feet of another ZonePlayer--less if you're beaming through walls and floors--to maintain the wireless connection. If your home has structured (built-in) Ethernet wiring, all the better; wired connections usually offer better performance, especially when the rooms to be connected are too far apart to allow strong wireless signals.

Because each ZonePlayer is a 50-watt-per-channel amplifier, all you have to do is attach a pair of speakers. However, people who already own nice audio equipment might choose to attach a ZonePlayer to the main stereo; it's a waste of the ZonePlayer amp, but it allows the digital music to be played through what may be the best sound system in the house.

On the downbeat, not all music files will work on the Sonos system. Standard MP3, AAC, WMA, and WAV music files all play nicely, along with Internet radio stations. But if you buy most of your music through the iTunes Music Store, MusicMatch, the MSN music store, or any of the other online services that encode songs with digital-rights management (DRM) copy protection, you'll have to go through the tedious process of converting those files to regular MP3s before you can play them through the Sonos system. So-called lossless formats also cause the Sonos to choke.

One exception: Real Network's Rhapsody online music-on-demand service plans to be Sonos-compatible within a few months, copy protection and all.

Although pricey, the Sonos system is the missing link in the evolution of digital music in the home.