KORG PA4X 76 - Manual (Page 466)

462| Customizing and editing the Sounds
3 Use the Curve radio buttons to specify how the volume will change in the
crossfaded region.
Curve Meaning
Linear The volume will change linearly.
Power The volume will change non-linearly. Sometimes a setting of Linear
will produce the impression that the volume has dropped in the mid-
dle of the crossfade curve. In such cases, use Power.