Using my car sub in my home theater?

I agree with "maniac". However if you wanted this to work you should first wonder if this is worth the time, effort, and money to be spent to make it work. A good AC-DC converter with enough amp and regulator is not cheap. I tried this before and I did make it work but wasn't satisfied by the result. If I have waited a little bit longer, the money I have saved plus the money I spent because of my curiosity equals a decent HT subwoofer.