Hi, I tried looking for an answer to this question on the forum but couldn't find one, so here it goes. I'm really new to the audio scene, and I'm starting to use REW. I have a USB interface and a SoundID measurement microphone. I did the soundcard calibration, and I have the microphone calibration files. With both of this information, shouldn't it be possible to obtain the SPL value directly? To use the SPL meter, do I have to calibrate it against an additional SPL meter. Is this true? Am I doing something wrong, or am I missing some software tool?