Dear Lleall: For what you posted SVS suggested that crossover frequency thinking to handle the main speakers fully: this means with out cut its natural frequency response and this is not what I recomend.
What I recomend is that your main speakers works from 80hz and up liberating it through a crossover from frequencies from 80hz and down and this is IMHO the main reason why add subwoofers to any passive loudspeakers. TO IMPROVE TO LOWER THE MAIN SPEAKERS IMD AND THD and obviously improving the IMD/THD system performance.
That is the first target and second target is to achieve better quality bass management with a third target that is to go deeper on bass with better quality.
Regards and enjoy the music,
R.
What I recomend is that your main speakers works from 80hz and up liberating it through a crossover from frequencies from 80hz and down and this is IMHO the main reason why add subwoofers to any passive loudspeakers. TO IMPROVE TO LOWER THE MAIN SPEAKERS IMD AND THD and obviously improving the IMD/THD system performance.
That is the first target and second target is to achieve better quality bass management with a third target that is to go deeper on bass with better quality.
Regards and enjoy the music,
R.