Sub wiring help needed - LOCs

I am going to be putting a sub in my truck and have factory Nav. I have the sub and amp picked out, and I am going to build a box for them. I will get a sub wiring kit to power the amp.

But my questions are,
1. I need a line out converter, but what would be a good one to buy and where do I wire it in? I think I have read to wire it before the factory speaker amp located under the dash is that correct?

2. Where do I tap into for the On/Off signal wire for the amp?

Any help would be greatly appreciated

This is the sub I will be using
Rockford Fosgate P3SD2-12 Punch Stage 3 shallow-mount 12" subwoofer with dual 2-ohm voice coils at Crutchfield.com
Along with this amp
Rockford Fosgate T500-1bdCP Power Series mono sub amplifier — 500 watts RMS x 1 at 2 ohms at Crutchfield.com
Put into a home made 1 ft^3 box

I've never used a outline converter so no help on question 1, but on ur amp u can tap the remote wire into any "key on" powered accessory.

Any thoughts on this Line out converter? It has the remote turn on for the amp On/Off built in. Does anyone thing that will cause any distortion in anything?
http://www.sonicelectronix.com/item_23128_PAC-SOEM-T.html

I went ahead and ordered the LOC I posted.

im doing a line out as well. Going to tap into my oem subwoofer power/ground/acc.

do you have any pics of yours?

the easiest way is to get an AMP like some of the MTX and others that has line level and RCA inputs and it will turn on when it senses a line level input

takes out a bunch of wiring