Quick question with wiring...

So my buddy told me that there is this thing that you plug into an empty spot on your fuse box and you can connect something to the wire with that. would I be able to run powerful my stereo with one of those? and if so where can I buy one? and more question,I have ballasts for hids but the bulbs were 9006 because they were in my other car..would I be able to use those same ballasts and put 9007 bulbs in them?

I believe he's talking about an add a fuse.

Why wouldn't you use the existing power to the radio? Oh..wait, you didn't mention what you drive.

well if its 04+ i just went through this on an install, i couldnt get power to the deck through the harness so i had to do my own. the switched source works but your constant is out. correct?

I drive a 99 GT. And the wire thats supposed to give the radio power is broken somewhere