Apple Power Macintosh 7300 series - PC Compatibility Card - Manual (Page 121)

Connecting the CD In cable to the CD-ROM drive
26 Plug the audio cable you threaded through the computer’s chassis (in step 20) into the
back of the CD-ROM drive.
(top, back of computer)
121 Reinstalling the PC Compatibility Card in Your Power Macintosh 7300 Computer