Alarm going off...

Solution
If you can replace the vibration sensor on the window with one that has adjustable sensitivity that will work.
Other options are to move the subwoofer away from the window, turn the sub level down, or put a heavy drape or padded window shade over the window to cut down the vibration.
If some vibration is transmitted through the floor then isolating the sub from the floor might help. There are professional platforms for this that will usually improve the quality of bass as well.
Turning the alarm off when you use the HTS is the last option.
If you can replace the vibration sensor on the window with one that has adjustable sensitivity that will work.
Other options are to move the subwoofer away from the window, turn the sub level down, or put a heavy drape or padded window shade over the window to cut down the vibration.
If some vibration is transmitted through the floor then isolating the sub from the floor might help. There are professional platforms for this that will usually improve the quality of bass as well.
Turning the alarm off when you use the HTS is the last option.
 
Solution