In your case, it is usually the problem of the active subwoofer. First of all, you rule out the speaker and the signal line of the speaker. The active subwoofer is equipped with a power amplifier, which may be the problem.

There is always noise on that side when you change the speaker. There is something wrong with the output interface of the subwoofer, which may be caused by the damage of the filter capacitor or resistor in the power amplifier, or the damage may be caused by the overload of the DC input of the strong pulse voltage, which leads to the instantaneous breakdown of the capacitor resistor. There are many capacitors and resistors in it, even if one or two are broken, it will work, but this phenomenon will occur to you.

please check whether the power supply voltage in your home is stable, because when you switch on and off the speaker, the current and voltage will pass through the subwoofer instantly. If the voltage is too high, the transformer inside will output DC to the lower side if it is not handled in time, which may damage the components inside over time. I suggest you take it to the "hospital". You can't handle it yourself, and the maintenance cost is very low.