If you want to use your car's amplifier and subwoofers on your home stereo or computer how can you plug either a 300W amp or a 1200W amp to a 120V house outlet?

You can't plug a car amplifier into a 120V house outlet. You must first convert 120V AC to 12V DC, then plug your car amplifier into the 12V DC.

Answer

It has been stated that: "The best thing you can do is plug all your car's equipment into your home's "12v" outlet. The result will be all your equipment will be destroyed immediatly and the populace will not have to listen to what you call "music". Maybe after the fire your Parents might care enough to monitor your computer usage. Now on a personal note, do what you can do well. If you don't know the basics about electricity, (Yes I am yelling!) DON'T GET NEAR IT!...pkazsr"

Although colorful, this may not be the answer you were looking for.

Assuming you meant "120v outlet"

There are many companies that make 12v "adapters" that will plug into your 120 volts AC (or even 240 vac) and convert it to 12 volts DC such as may be used by car stereo equipment. You just need to make sure you get one (or more) that has sufficient capacity (in watts) to operate, say, 20 percent more than the rated output of your equipment. In other words, if you have a 1000 watt amplifier, you should use a 1200 watt converter. This will permit the equipment to operate more efficiently, at a cooler, safer temperature than if you try to save a few dollars by buying a unit that is barely big enough. Disconnect the converters from 120v when not in use. Rock on! on side note if you have small AC to DC converter lieing around DO NOT USE IT !!! these can get hot if to much watts are trying to be pulled out of it and plastic does cach on fire DO NOT TRY THIS

Answer

Step 1: take amplifier to pawn shop.

Step 2: trade amplifier for a home-stereo integrated amp. This will probably require some money.

Step 3: use that to drive the sub. Yes, it will work.

This will work better, and for less money, than trying to use a power supply to operate the car stereo amp.

but if you must have your car stereo you can get AC to DC converters big enoth to power your amp and stereo at this link ROCK ON !!!!!!! http://www.carparts.com/PYRAMID-110-VOLT-AC-TO-12-VOLT-DC-POWER-CONVERTERS/GP_2001690_N_111+10718+600022513_10618.car

Buy a heavy duty marine deep cycle battery and hook your amp up, and then buy a battery charger to charge it overnight.

I have an 800w installed with my comp. boom box and everything.

Answer

I have made a home stereo out of car audio equipment before. I wanted to because of the sound quality in car audio. I have gone over the other answers in this page and have yet to see anyone that stated they know anything about electricity say anything about the Amps needed to properly run car audio equipment. Ever take notice that in your automobile you require a 30 - 35 Amp fuse and in some cases multiple fuses. If you don't have the sificient amperage in your converter your sub will crap out as soon as it starts to sound good, mind you if you don't want to add a sub ( and Actually enjoy your music ) then you wont need much in the amperage side. If you are not running anything but a deck then a low budget 12 converter will do the job. to get an inverter with sificient amperage to run amps, subwoofers, eq's and such, it will run you around $700.00 - $1,000.00 just for the converter alone. Trust me I have done it. The sound is like none other and the fine's for the noise complaints are great. Hahahahaha. I havent turned my system on in years as I get a fine everytime. But it was fun at the time. Best sound ever.