Apple PC Compatibility Card - Manual (Page 41)

41 Installing the Card in a Power Macintosh 7200, 7300, 7500, or 7600
19 Plug one of the two identical SCSI audio cables into the connector labeled
“REV_SND_OUT” (Reversed Sound Out) on the PC Compatibility Card.
IMPORTANT Use only the cables that came with this PC Compatibility Card.
Do not use cables from other models of the card.
Your PC Compatibility Card came with three audio cables. They may have
different colors of tubing near the ends to help you tell them apart. You’ll
only be using two of these cables (the third one is for a different kind of
CD-ROM drive). Two of the cables have identical plugs on the end, as shown
below. Use one of these two identical cables for this step.
Audio cable plug for
SCSI CD-ROM drives