Some crossovers do have settings you can play around. Mid flat, high, -1 db etc...
Before I went active, I had a set of Alpine Type X components. You could measure the distance and angles to the drivers and the manual would have recommended crossover settings based upon your measurements. There were a LOT of jumpers in the crossover which allowed you to do this. Below is an excerpt from the manual.
"WF-LP:
In addition to functioning as a low-pass crossover, this section also serves as a part of the phase and
response compensation section of the network. By adjusting the phase within the crossover region, it
is possible to achieve “phase linkage” with the tweeter, producing a seamless blend or transition
between the two drivers. This is affected mostly by individual driver placement in relationship to each
other, but also by relative distance to the listener
WF:
Functions as off-axis compensation, by changing the upper frequency response in order to
compensate for natural roll-off when the listener is off-axis.
TW-HP:
In addition to functioning as a high-pass crossover, this section also serves as a part of the phase
compensation section of the network. By adjusting the phase within the crossover region, it is possible
to achieve “phase linkage” with the woofer, producing a seamless blend or transition between the two
drivers. This is affected mostly by individual driver placement in relationship to each other, but also by
relative distance to the listener
TW:
Functions as off-axis compensation, by tilting the frequency response to correct for natural roll-off
associated with extreme listening angles. Additionally, it also serves to allow precise level adjustment.
Signal Link:
The signal link section provides a parallel connection between the input sides of the terminal blocks,
allowing the input connection to be made at different terminals. Caution: These jumpers must be
removed when used in bi-amp configuration to prevent possible amplifier damage."
