IIRC when using REW you're supposed to feed it the response curve of your mic (which you should get at least as a printout with any good mic) + also do a loopba

IIRC when using REW you're supposed to feed it the response curve of your mic (which you should get at least as a printout with any good mic) + also do a loopback measurement of your audio input. Or skip both and assume they're "neutral enough"