I'm trying to build a low cost hifi (Hiraga Le Monstre) but I have two old computer PSUs at hand so I tried to use it as power source. The Monstre needs +12V and -12V, computer PSUs have both, but the negative output can only supply 0.8A or so, which is probably not enough.
My idea was this. PSUs are supposed to be galvanic isolated. Which means I should be able to connect one's GND to the other's 12V and use it as a floating common ground without burning something and getting -12V referenced to the common at the original GND. Seems like my plan fails somewhere. I was cautious and connected the two PSUs through a 630mA fuse, which burned when I turned them on. Both units worked independantly so they didn't break, only the fuse burned.
What was I missing? Or any ideas how to get it done safely?