I recently acquired a DefTech Prosub 1000, but after hooking it up to my amp, and turning on the power, it produces a low hum that changes from time to time. When music or a movie is playing it intermittently thumps really hard (as though its working well) and then quite's off again. The low pass filter on the back and the volume on the side work fine, its just not performing.
The sound, that generated when no music is playing and when its plugged in is a low hum, that will get loud and then go back to quite and occasionally go right out for a few moments (seconds).
Any help would be greatly appreciated!