Music on the move.(CD players, MP3 portables)(Buyers Guide)

If you want to be wired for sound wherever you go this summer, you'll find an ever-widening selection of personal music machines. The leading devices, the portable CD player and MP3 player, generally produce superb digital audio signals--though the headphones supplied with most players don't do justice to them. You should choose a player, then, according to factors other than audio performance; the format of your music collection, for example. The portable CD player is the obvious choice for most people, given the ubiquity of the compact disc and the design of players, which are now slimmer, more resistant to bumps, and less wasteful with batteries.

Compact MP3 players and some new hybrid portables--CD players that also handle MP3 discs and digital jukebox players, which double as hard-drive-based music players for home-entertainment systems--hold songs in the form of computer files, usually in the MP3 format (the acronym stands for Moving Pictures Layer 3). That allows these players to carry a mobile, customized selection of music. However, assembling that music program requires a computer, preferably with a high-speed Internet connection, equipped with software to extract and organize music in file format from CDs or web sites. You also need time and patience to transfer files from the computer to the portable player.

It's time-consuming even to track the ever-changing sources of digital music. After a frenzied period in which consumers flocked to share music online, Napster and other file-sharing services appear to be losing a legal battle with the major record companies, which claim such activity violates copyright laws.

Consumers Union, the nonprofit organization that publishes CONSUMER REPORTS, recently urged Congress to approve legislation that would allow consumers to continue to easily share music files online in exchange for paying a reasonable fee to compensate copyright holders.

More and more record labels are beginning to offer digital music online, usually in deals with music-oriented ...