Got hold of 2 identical bench power supplies..each one is 80 amp continous, regulated DC switching power supply..each one puts out 13.8 volts...not adjustable. What is the proper and safe way to wire them together (parallel) to achieve 160 amps overall current output...(if there is a safe way) ? Do I just connect the positive terminals and nevative terminals togehter ? I tried that and they started to make a sharp "schrill"-type noise...so I quickly disconnected them. They both are very good quality power supply's with digigal readouts and each perform very well when operated alone, but I would like to achieve higher amperage. Is this possible to do ?