One Subwoofer channel not working, what effect?

It seems the left channel of my subwoofer isn't working. When I connect it, the whole system starts shutting off and on, when I disconnect the wire from the sub, the problem stops and I still get output from the sub, with no noticeable hum or distortion.

Does this sound like a problem with the sub amp? If so,what effect does is this likely to have on output? When bass frequencies are recorded, I know that both channels are used, but do engineers typically record significantly different bass information for each channel, even though lower bass frequencies are not perceived directionally? I hope this question makes sense at least. If not, please help me understand what I need to be thinking about.

Thanks as always you smart lil' audiophiles.
How is your subwoofer connected to your pream-processor?
Thanks for your interest. I re-posted the thread under "Help! Only one subwoofer channel working."