no! but I'd expect any passive crossover to exhibit varying phase shifts as the frequency changes ... so for me it's back to "if it sounds good ..."Have you actually measured the response with the sub out-of-phase?
Many prefer that position because it creates a dip at the cross-over frequency, so deep bass is not masked by low-mids/high bass.
Correct and the generally accepted way to change an x.1 system into x.2 is to add a second sub ... nothing about the signals differing for sub 1, sub 2, etc.The .1 in x.1 means there's only one sub signal,
Usually it's because you have a patchbay ...Now I don't get why he wants to connect it to the patchbay...