Subwoofer manufacturers do not want to scare you out of buying their product by telling you you have to spend another 3 or 4 thousand dollars in cross overs and wires to get their sub operating right.
True, it is partially about the money, but not my primary reason. Primarily, I really like the Sabrina X and didn’t want to ruin what I heard. If I can’t integrate the subwoofers, I would probably purchase Wilson’s crossover..but for now I need to work on power conditioning and room acoustics.
I should add that I believe that with a perfect crossover the Sabrina X would be relieved of that 1 meter 31 Hz requirement and the sound would improve,, but what crossover and which interconnects?