no, you cannot use an audio amplifier to power your computer...
the amp has one purpose; to amplify an audio signal. the M2-ATX has very different purpose(s); to provide regulated multi-rail power to the computer, and to provide automatic startup/shutdown control.
I highly suggest you do more :research: before you purchase ANYTHING!! I'm not trying to discourage you from asking questions (in this case, it's a good thing you asked first ), but you obviously need to learn the PC/carPC basics before you start buying anything (or you'll likely end up buying components that are incompatible with each other). read the FAQ sections first (and don't say you have already, because the first FAQ topic (power supplies explained) would have answered this question for you )