Yes. Most head units only put out about 15-20 watts RMS, you need more than that to properly power a subwoofer. Ignore peak ratings, only use RMS ratings to match everything together.
you need an amp and an amp wiring kit
First you will absolutely need an amp to power any subwoofers. Nowadays subwoofers come along with amp..& normally one 1200watt subwoofer decrease your car battery lifetime to 2-4 month
To power your speakers, and to ensure that your amp has enough power to power your subwoofers, you would need at least an amp of 750 watts true power.
you need an amplifier first. decide where you want the amp, and wire it to that point. (amp comes with instructions for the wiring) once the amp is wired in, wire it to the radio(instructions come with amp) and screw it in. then locate where you want the sub(s) and wire it to that from the amp. almost all your instructions for installing subwoofers comes with the amp.
Yes
Well, if they share a box, then you will need to make sure that your amp RCA's are connected to the back of your CD players auxillary ports. Then you will need to run the power wire from your amp to the battery, and you will need to find a nice ground on your from somewhere. Then connect your remote wire. After all that, you will need to connect your box, or boxes, to the amp. In which case, you will need to make sure that you have the positive and negative for the amp and the speakers alligned right. DO NOT BRIDGE UNLESS YOUR SPEAKERS SAY THAT THEY ARE CAPABLE. I cannot stress that enough. Anyway, that's about it.
Memphis Street Refrence 1.500 best amp for the subs
either your amp has a short..... or.... you have a bad ground
you now need an amp that will power them both and a wireing kit and a box or 2 to put them in and a place to put them.
jut an amp wirering kit a wirering harness for a 09 sonata and a dash insert for 09 sonata.
bridge amp run 1 sub it will hit deeper and harder start adjusting with gain all the way down
if you want to use your stock head unit to run your subwoofers you can go to any car audio shop and buy a converter that will splice into your rear speakers and convert the signal to use the RCA cables for your amp.