I have one of those, altho I have not taken it all the way up 60V. Generally the voltage listed is the "Generally Accepted Multiple of 12V Values" of voltage. However, you can't always go by that statement.
And unfortunately, you can't just "hook it up and let's see" kind of thing because if the voltage is too high, things go pop.
I don't have immediate access to mine, does your happen to have any kind of model number listed anywhere on the case? I'm guessing no, but worth a shot.