Zenith introduced new consumer electronics devices Thursday at the Consumer Electronics Show in Las Vegas. Among the devices were two new DVD players, one single-tray model for $160 that will be available in April, and a disc-changing model for $300 that will be released in August. Both can play MP3 files on discs and are compatible with DVDs, CDs and CD-rewritable discs. Another $250 DVD player expected out in April will include a VCR and will play MP3 files on discs. Zenith has also released its $900 portable DVD player with a 7-inch liquid-crystal display.