zapco DSP-Z8 IV II Owner's Manual page 16

On the Crossover page you can customize the
crossovers to fit the needs of your individual system.
You have all the choices of crossover styles and
slopes that the PC GUI has by using the drop-down
menus in the parameter boxes of each channel.
The mobile apps do not have the crossover link
functions of the PC, so each channel's crossover must
be set individually. Left/Right channel pair should
always have the same crossover.
The Delay page lets you enter the distance from the
listening position to each speaker in centimeters or
inches and immediately gives you the applicable
Delay in milliseconds for a rock solid and accurate
front stag.