After about a year or so with another ID brand of subs in my theater i noticed a problem when watching " the conjuring" last nite. Red line bass instantaneously, then gone, in this soundtrack.
My sealed subs werent as snappy as I had become accustomed to. Upon closer inspection, the screws holding the driver in place had worked loose. One sub much worse than the other. Bot needed tightening. Two full turns on the bad one.
Tightness restored along with performance.
Worth it for a point of maintanence to check now and then.