I feel that the unit doesn't like mixing odd an even order slope. For example, everytime I do 6dB (or 18) HP and 24dB LP between mid and subwoofer would always guarantee an out of phase result AND off-center imaging. Flipping the phase works, but not with bass coming way from behind. Putting it back to 12/24 or 12/12 always work fine and they integrate nicely. Don't know if it's the same on my mid/tweeter (currently at 6H/12L) because I don't know how to distinguish between in phase and out of phase mid/tweet. I may switch to 12/12 in the future.