Well, in MOST cases things have gotten more standardized these days. In other words, if it fits, it works. The place where you plug your cord into your amp would be shaped differently if it were rated differently. As would the plug and/or receptacle in the wall. Also, the amp will only draw what it needs. Power isn't forced into an amp. So, as long as you plug it into a receptacle that matches the voltage rating of the amp, you should be fine as well. For instance, if you plug a 120V head that can handle 15 amps into a 120V 20 amp receptacle, you are still OK because the extra 5 amps aren't shoved into the amp. It draws what it needs. (For those in the know, I am an electrician and electronics student. Yes, I get that my explanation is way over simplified. No need to get into the weeds over such a simple issue.)
Short version: You should be good to go.