The complexity of the X-over will effect amps differently,as the back EMF will have different phase angles.Simple 6db/oct reduces this effect and is more agreeable to small set amps.
The order of x-ver is generally determined by the drivers used,their frequency response and resonances outside their operating spectrum.Many manufacturers will take a great tweeter and run it as low as possible using 3rd and 4th order x-overs.When using these crossovers the mids or woofer are wired out-of-phase to bring them back into phase.
I believe simplier is better,but when designing a 6db/oct system,sometimes it is best to use a L-pad on the tweeter.This prevents the x-over from changing as the impedance of the driver changes over its' range.Having just built a speaker system of this design premise,I understand the difficulty involved.Frequency respomse abnormalities,over excursion of drivers and phase coherency are all balls to be kept up-in the-air during the juggling routine.
The order of x-ver is generally determined by the drivers used,their frequency response and resonances outside their operating spectrum.Many manufacturers will take a great tweeter and run it as low as possible using 3rd and 4th order x-overs.When using these crossovers the mids or woofer are wired out-of-phase to bring them back into phase.
I believe simplier is better,but when designing a 6db/oct system,sometimes it is best to use a L-pad on the tweeter.This prevents the x-over from changing as the impedance of the driver changes over its' range.Having just built a speaker system of this design premise,I understand the difficulty involved.Frequency respomse abnormalities,over excursion of drivers and phase coherency are all balls to be kept up-in the-air during the juggling routine.