MP3 players have gotten flashier, sleeker, and more futuristic. But only one can claim the distinction of being retro-chic. The $250 Duo-Aria MP3 player by Digisette (973/455-7084, www.digisette.com ) looks decidedly nondigital, camouflaged as the audio standard of yesteryear: a tape cassette. But this incognito USB device is, in fact, a full-fledged MP3 player with 32MB of on-board flash memory (expandable to 96MB with a 64MB SanDisk MultiMediaCard). It works as a stand-alone player, or you can insert the Duo-Aria into virtually any tape deck--your car stereo, say--to keep the music playing. A rechargeable NiMH battery allows for six hours of music or nine hours of speech. The Duo-Aria has some drawbacks--for example, no LCD screen, making it awkward to navigate a playlist. And if you're hoping for the triumphant return of another old audio standard, we're sorry to disappoint you: an eight-track cartridge version is not in the Digisette pipeline.