paradigm problems - pdr10 subwoofer (1 Viewer)

[Richard cash]

i have recently added the sub to my system which i got for £150. At the back of the sub, along with all the other inputs there is the power swith which says on/auto or off. The problem is then i watch a movie it is great, apart from the slight hum, but when the movie has finnished and i turn off my amp the subwoofer makes a really loud, low frequency humming noise, it pratically shakes the whole room. This is quite distressing as it is supposed to be on auto mode now. The noise continues to grow and i have to turn it off, its too unbearable.
The power cord can be detatched from the subwoofer so i did that and found that there is only two pins coming out of the sub but the cord has three holes in it. This made me think that it might be an american sub. I asked my dad if he knew what is might be and he said that it was probably not discharging properly. I dont really have much of an idea and need you help in solving the problem
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[Ariel]

check for the grounding. if you connected the sub using the line input, the rca plug might not be inserted properly.