If the Earthworks answered that their microphone does not need a calibration file, then that's good. So you have a good microphone. But you can check it. Find someone near you who has a microphone with a factory calibration file, arrange to measure both microphones on the speaker that can produce the widest possible frequency range, and compare the graphs. The measurement conditions for both microphones should not be different. The same distances from the microphone to the speaker, and everything else is the same.