You’ll be just fine with the Monoprice 14 gage, 15 foot power cord. I’m using that exact cable and length for one of my subs as well. It was like 10 bucks.
Long power cable for subwoofer
I'm thinking about moving my SVS SB16s and require longer power cords, about 15 feet. All I've found in the 10awg range were like 6ft or 2 meters. Even Monoprice doesn't have anything that's not 18awg or maybe 14awg. Does this really matter? I don't want to spend tons of $ on subwoofer power cables.