5v or 6v on ubec?

[What's_nitro?]

You can set the amperage to whatever you want. Amps aren't what destroys electronics, volts do. The servos only draw the current they need. Too much voltage forces them to draw more than they can handle and that's how they get fried. High-Torque, high-speed, or digital servos usually draw more current, but never anywhere near the 3A continuous rating of most UBEC's.