But changing relative, adjacent crossover slopes does affect phase when the adjacent drivers play together.
If the measured curves match the classical curve chosen (as represented with the crossover targets in the EQ section with no house curve applied), they will sum predictably.
When a house curve is used and the drivers are playing at different relative levels, this changes things.
I am trying to set a target for the slope of the crossover given that I am not building a flat response at the speaker system level in an anechoic space, but rather a response that correlates to the house curve at the listening position. This is what must be done in a car for correct perceived sound reproduction.
I am not the first person to model crossovers with REW in this way. What I want to know is whether the shift observed in the target curves corresponds to what would be seen modeling with a flat target and applying the eq for a house curve after the fact. There are reasons in a car that this would be easier to do “backwards”. For one, preserving available eq bands (given that some will be spent matching the curve). For another, reducing trial and error.