Making a standalone 12v power supply from a PC power supp... I'm toying with the idea of making one to power a small car amp to run my MP3 player through at work. I know, I know. There are already things made to amplify audio from MP3 players for listening without headphones. But they cost a bit more than I'd like to spend. I figure I can make one for around $10 (I already have the amp and power supply) I've read up on it a bit elsewhere on the web, and it seems alot of the RC plane guys build them to power their RC battery chargers. Doing the math, a 170 watt amp will draw about 14 amps, and a 200 watt computer ps should be able to output almost 17 amps. (both at 12v) I think I may need to sort through my PC boneyard box in the basement to find a bigger ps, but it all seems do-able... It's looking like I could also wire the 5v line to a USB plug to power the MP3 player to boot. Any thoughts, or has anyone made one of these before?