The 12V rail will provide enough current to most speakers, however, be aware that you're likely to pick up noise on this rail from other PC components. Make sure to filter it well or you will hear a buzzing sound in your audio when things like HDDs power up.I'm thinking in doing about the same thing, but with the diference that I want to use the Molex and the +5v and +12v for supply the current to my speakers and maybe a switch. If my PC power supply have enought watts for all this shouldn't be a problem, or can it be? (As long as the correct voltage is supplied of course)