In an addition to your Line Out Converter, you need to make sure you have all the right parts such as an amp wiring kit. You can pick these up at any Car Stereo store such as Best Buy or Circuit City. The Amp wiring kit includes:
- 1Power wire. I recommend at least 8 gauge. Ultimately it really depends on how many watts you push.
- 1 Ground wire.
- 1 Remote wire.
- 1 set of RCA cable.
Connect and run all the necessary wiring. It entails the following:
-Connect and run Power wire from car battery back to the amp.
-Connect Ground wire to metal surface somewhere in the back of your Xterra then connect to amp. (note: you may have to search a bit to find a solid ground. *Make sure the ground wire is touching bare unpainted metal).
-Connect Remote wire to a wire that turns on when the Vehicle is on. You may have to tap into an Accessory wire.
-You will use the Line Out Converter and RCAs together. I assume its a 2 channel converter. I recommend placing the LOC behind your Factory Cd player. First, you will need to TAP into the Left rear and Right rear speakers via the Cd player (search for wiring diagrams). Basically what the Line Out Converter does is take the - and + signals of the left and right rear speaks and enables you to plug in the RCAs and then run them back to the amp.
After all that you should be good to go! Please note that I am not a professional installer and am not responsible for any damage you may cause to your car. When in doubt about connecting any audio equipment seek professional advice (i.e. - take your car somewhere and have it done). 
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/Oo ___Maxima___ oO\
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