yup and if it's not right, you'll lose spl in the crossing region due to cancellation between the Neo 10 ( or whatever driver you're crorssing to) and the sub section.
If one is playing music on the Super 7's , say some acoustic guitar, and someone rotates the phase setting, it's really easy to hear the body/life disappear
Ideally, you'll measure the speaker on it's own to determine the -6 db point. Then, measure the sub on its own, match the overall response spl to the speaker with the volume control (sub amp) and then using the c/o setting, match the -6 db point of the speaker. Next, measure the speaker & sub together and note the result at the cross over point, it should be raised to match the overall response. If it does not, adjust phase to reduce the cancellation.
fine tune from there
jay