First off, please excuse my stupidity. I've decided to add some simple 6x9s to my stock system which is a 4-speaker setup. They're listed as "2-70 watts RMS (210 watt peak)". I have 2 questions. Do I need any kind of amp to run them? And, How do I know if I can hook them up to my stock header? I'd prefer to keep it as stock as possible. Please, don't be insulted by my ignorance.
You don't necessarily need an external amp to run them. You can hook them to your stock stereo using the preexisting wires if you want. An external amp would probably sound better and you'd be able to get higher levels of clean sound from the speakers with an amp, but it's not required.
Are you adding 6x9 speakers to the rear and leaving the front speakers stock?
OOohhh...misunderstood the question there. By 'add' I assumed you meant 'replace', sorry.
I'm not sure if there's any way to straight up add additional speakers to a stock system. I'm thinking that if you tried it would mess up the load on the amp in your stereo, so your best bet is to get an external amp.