Useing Multiple PSU's as ACDC power converter

[oplin]

In theory this sounds like it should work just fine but I'm not expert with electricity. What i want to do is get 12volts with around 50-250amps output. What i was thinking was taking several cheap or half way decent psu's wiring all the 12volt line in parrellell ( or series) so that the amps add together. This would be used to power a amplifier or several amplifiers. I looked at acdc converters and those things are freakin expensive so i was hoping i could do it with psu's for a fraction of the cost.