wait, I think you're confused about what a member said. He said to stop buying Duals.. He didn't mean the voice coil configuration. He was talking about the brand Dual, which is regarded very poorly in the audio community. He was implying that your sub was crap, not to change from dvc to svc.
Also, on your amp speaker outputs, you have the wires in the center 2 channels. It clearly says above the outputs that you need the speaker wires on the outside 2 channels. I don't think this has anything to do with your problem, but you probably just got a crap sub. put that DMM on the speaker outputs of the amp and play a song on the head unit. it will tell you an AC voltage that the amp is putting out to the sub (it will jump around because the rythm isn't constant bass unless you use a song like "put on" or something). Your sub wants 800 watts and wires down to 2 ohms so you take the square root of 800x2 to get the voltage you should be seeing at the speaker outputs terminals. In your case, sqrt(1600)=40V so the DMM should NOT be seeing over 40v.
It is best to do this with a constant test tone to record an accurate DMM measurement.