You might try the ones at http://www.macdrivermuseum.net/disk.shtml

However, the primitive audio subsystem in the Classic may not successfully convert 16-bit stereo into 8-bit mono at speed, so if getting the Classic to play audio is your goal, you may be disappointed. But using the Classic only to control playback of audio tracks, and getting said audio directly from the CDROM drive is eminently practical (I use one of my Pluses for precisely this task, making the combination the world's most ungainly CD player).