I am currently in the process of building my box which will house 2 10" JL 10w3v2's powered by a JL 500/1 amp.

What should I look for in in a Line Output Converter (LOC) since I'm a noob to this?

Thanks.

 

Go with the Navone LOC, it's top notch quality (Dave Navone is an expert in the car audio field for many years, and he is very helpful with any questions you may have.)

Here's the link to the one I used:
http://www.davidnavone.com/adaptor_products.htm N-774(or now NE-774)