crossover and subwoofer

[jimmymack]

I'm just starting my dj business and have been buying equipment. I have two jbl eon 1500 passive speakers powered by a crown xls 402 amp. Also a Newmark two channel mixer. I recently purchased a jbl jrx 118s passive subwoofer. I am looking to buy a separate amp to power the single sub. My question is how to connect the separate amp into my system. I feel I will need an active crossover as I don't think the sub has one. The mixer has rca connections for which I'm using two rca males to xlr males between the mixer and my primary amp. Any help in the cables needed and connection process for the sub would be appreciated.

Sincerely,
Jim aka Jimmymack