I have a focus that im trying to put a sub into. Now i have the sub, but soon im going to get a amp. Its a lignting audio 300w sub, with probly, a 300w amp. Now my question is the sub is already hooked up to the system, but not through the sub output on the header, i really dont want to screw with the stock header and i dont even know if it has a sub output, so can i just rougt the amp to the sub, and not have to go through the head unit?
a "header" is a part of your car's exhaust. I wouldn't suggest putting an amplifier on that. It's loud enough already, hence the use of a resonator and a muffler.
I know whqat you meant. My point was to use correct terminology and not make up words to be lazy. I don't call an amplifier a spark plug, either. All you accomplished was to be confusing.
if you have a stock head unit, you won't hae any line-outs. you'll need to use an amplifier with speaker-level inputs, or a line-out convertor (LOC)
There will be a difference, how big it is depends on your ears. Basically, a head units amp is providing the signal with speaker outs, and a head unit's amp will have more distortion and will clip quicker than RCA preouts will. Preouts have a much cleaner sound.