Using a REL Storm with a Spectrum Amp?

I have a Spectron Musician 3SE Mk2 amp and I have been using full range speakers. I am demoing a set of monitors and an REL Storm III sub. Does anyone out there see any problem with running the sub by using a Neutrik NL4FC cable from the sub to the terminals on the Spectron...where the the positive and negative leads would be connected to one side of the amp speaker terminals and a single wire connected to the negative terminal on the other side? Just want to make sure all components are protected!
Why wouldn't you just connect the sub to the preamp outs and not worry about possibly shorting the amps outputs?
Rwwear: The Neutrik option is one of two, the other being a Y connection from the RCA preamps out. The difference is the Neutrik cable is way longer and allows more placement options for the sub than the preamp-out option.
I don't quite understand why you would want to connect the extra wire to the negative terminal. The positve and negative wires will be connected to their respective counterparts on the amp?
Rwwear: I share your not-quite-understanding the arrangement of connecting the extra wire to the negative terminal. The Storm III manual in conjuction with use of the Neutrik cable has that instruction (only 3 wires on the amp end)...and intuitively it didn't feel comfortable. I did try the RCA pre out to sub and functionally all is well. Still wonder who else out there may have used the Neutrik option and wonder if it makes any sonic difference...aside from sub placement options. Thanks for your counsel.
I have a Storm III and have connected it to several amps using the Neutrik cable. This method is much better in my experience than using RCA interconnet to pre-outs.

The correct way to connect it is Red wire to the Right + terminal on your amp, Yellow Wire to the Left +, and Black Wire to either right or left - terminal. If your amp is a fully balanced design then the black wire needs to be connected to a ground point on the amp chassis, not the speaker - (on my Ayre amp I connected it to a chassis screw).

I'm not familiar with your amp, is there something special about it that causes you to thin + and - terminals should be reversed in the wiring scheme?

Bdgregory: Thanks for the perspective with your experience. Regarding the wiring are correct...I misread the manual. Third (yellow) wire to the +. There's a reason I sought a reality check before hooking up components. I guess the carpenter's rule applies here as well: Read twice, attach once. Thanks.
Mdrummer01 . . I understand. I was a little tentative the first time I connect my Storm up. 3 wires throws you when you expect 4 . . .