Which output terminals are required for the subwoofer?

 In the case of an active subwoofer, the necessary input and output terminals include a low-level output terminal and an input terminal (some also have a Link Out for connecting a second subwoofer) and a high-level speaker. Line input and output. Then there must be crossover adjustment, volume adjustment, phase adjustment or phase switching. A few subwoofers also have a high-pass output and a low-pass output. The so-called Qualcomm is to filter out the frequency band below the crossover point and let the frequency band above the crossover point pass. The so-called low pass is to filter out the frequency band above the crossover point and let the frequency band below the crossover point pass.