On the recommendation of Duke I am running ordinary 14g PartsExpress wire. I was skeptical. But, Save your money for where it matters, he said, basic wire is fine for low bass. Sure seems he got it right again. Another one of those things where what is so important at higher frequencies just doesn't hardly matter way down low. In any case, keep in mind all the great bass I'm getting is basically lamp cord.
Based on that I wouldn't worry much about the quality of your connection. If your subs have high level inputs then running cheap speaker wire will be cheapest. If they don't you can add a LOC from PartsExpress for about $6. Next after that, cheap RCA. Just don't see the need for XLR, not for this. Spend it something like Blue Quantum Fuses where it'll really make a difference.
Based on that I wouldn't worry much about the quality of your connection. If your subs have high level inputs then running cheap speaker wire will be cheapest. If they don't you can add a LOC from PartsExpress for about $6. Next after that, cheap RCA. Just don't see the need for XLR, not for this. Spend it something like Blue Quantum Fuses where it'll really make a difference.