What we’ll see this year in networked audio is just the beginning. Worldwide shipments of consumer electronics products with built-in networking capabilities will grow at a compound annual growth rate of 64.4 percent between 2005 and 2009 to 154.5 million units from 21.2 million, according to a forecast by market research company iSuppli.

By 2009, networked consumer electronics “will represent a significant portion of overall consumer electronics shipments,” the report said. Demand will be driven by the proliferation of digital media files, growing consumer awareness, and multi-room digital video records (DVRs),” which, when available, will deliver time-shifted TV programs to multiple TVs over Ethernet networks or no-new-wires technologies that transmit content over a home’s existing coaxial cables or electric powerlines. Some DVRs also time-shift music channels delivered over cable or satellite-TV networks, potentially enabling future models to distribute time-shifted music programs throughout the house over existing coaxial cable or powerlines. One such product was in development in 2005 but hadn’t shipped by early 2006.

Network Technologies 
Most networked audio products tap into a home’s wired Ethernet network. Some incorporate built-in "wireless Ethernet" technology developed by the Institute of Electrical and Electronics Engineers (IEEE). Often called Wi-Fi for Wireless Fidelity, the technology was built into select audio products for the first time in 2003. Alternately, consumers can plug low-cost Wi-Fi adapters into their products’ Ethernet ports to deliver wireless connectivity.

Similarly, consumers can plug low-cost “Ethernet-to-powerline” adapters into a product’s Ethernet port to turn their home’s electrical wiring into an Ethernet network. Many of these adapters use a technology developed by the HomePlug Powerline Alliance to let products communicate via a home's electrical wiring.

Some consumer electronics suppliers have developed rival powerline communications standards. At least one is robust enough to stream multiple HDTV programs simultaneously throughout the house.

With different suppliers pursuing different network strategies, and with incompatible media formats proliferating, the Digital Living Network Alliance was formed to help consumers sort through the confusion. The organization, with more than 240 member companies, sets minimum compatibility standards to assure consumers that PCs, consumer electronics and mobile devices marked with a DLNA-logo will be able to share digital content (including video and digital images) within a home network. The first DLNA-certified products are expected to be available in the U.S. in 2006.

Moving Music off the PC
Among networked audio products, DMAs that connect stereo systems to PCs are the most affordable, and they're becoming increasingly visible. Only a handful were available between 2000-2002, but their selection has grown to dozens of models at prices starting below $100. The selection includes a growing number of adapters from mainstream consumer electronics suppliers, who followed computer-peripheral companies to the market.

These devices also stream music from a growing number of NAS devices available from information technology companies to store audio, video, digital still images and other content. NAS devices cost less than many desktop PCs.

Consumer demand for DMAs is driven in part by the growing number of compressed-music collections stored on PC hard drives. Demand also is increased because of heightened awareness and the growing installed base of home PC networks. As of year-end 2005, home network penetration hit around 25 percent of U.S. households, up from the previous year’s 12 percent,, according to Parks Associates.. The company expects 32 percent penetration by year-end 2009.

The most sophisticated DMAs feature advanced menu systems, which let consumers remotely select songs by title, artist, genre and playlist via their front-panel display or a connected TV screen. In 2006, more than a dozen suppliers plan to offer DMAs that also display still images and/or full-motion video stored on a PC. Video could include TV programs stored on PCs equipped with DVR technology. The DMAs also stream music from Internet radio stations through a networked broadband modem.

In some cases, you won’t have to buy a DMA to network your audio system to a PC. That’s because a handful of home audio products incorporate built-in PC networking. In 2006, for example, AM/FM surround-sound receivers from several brands tap into Ethernet networks to select and stream music files from a PC in another room.

Central Music Servers Many networked-audio systems don’t rely on PCs or NAS devices as their music source. These systems use component-audio-style HDD music servers to stream different songs simultaneously to networked tabletop "clients" located in multiple rooms. Some clients connect to existing stereo systems. Some clients incorporate their own amplifiers and speakers. Other clients resemble all-in-one compact stereo systems with AM/FM tuner, amplifier and speakers included.

For these applications, music servers are priced from about $999 to the tens of thousands of dollars. Client prices start at about $199 without speakers or amplifier and about $299 with speakers and amplifier.

The servers store music from hundreds of CDs in such compressed-audio formats as MP3 and Windows Media Audio (WMA), delivering the music-storage capacity of CD megachangers that store up to 400 CDs – but in a lot less space and with near-instant access to every song. Many servers also store music in uncompressed CD audio form. All servers make it easy to find and play individual songs, thanks to music-management software that sorts and displays songs by album title, song title, music genre, or artist name.

In 2006, at least one HTiB system and one all-in-one compact stereo system incorporated music servers to stream multiple songs simultaneously to multiple clients.

Custom-install Options
Networked audio systems sold with tabletop clients are designed predominantly for the do-it-yourselfer. All you have to do is plug the components into an existing home Ethernet network (available in more and more new homes), plug a no-new-wires network adapter into the product’s Ethernet port, or buy an audio product with integrated no-new-wires network technology.

Many music servers, however, aren’t intended for the do-it-yourselfer. They’re sold by custom A/V installers who integrate them into multi-room audio systems, which distribute music throughout the house to speakers installed in the walls or ceilings. In each room, consumers use an in-wall or tabletop controller, or handheld remote, to turn on a central hi-fi system, pick a song from the HDD server, select a disc in a CD megachanger, or select radio stations.

Music servers for installed multi-room audio systems range in price from about $1,000 up to $20,000.

Whether for the do-it-yourselfer or for the custom installer, many music servers come with built-in CD player so you can “rip” CDs and transfer their songs to the HDD. For people with extensive CD libraries, however, the task can be time-consuming, even if the songs are ripped at 2x or 4x speed. For that reason, multiple companies now offer to do the ripping for you.