By reference levels I mean that you calibrate with DB-meter using static white noise to a reference DB-value. I have done it before, but I don’t seem to keep up with it, and do the “insane” volume knob riding all the time lol.
I read somewhere that when mixing professionally you should calibrate to around 75 to 80 dB (depending on room size). By always mixing at a specific calibrated reference level you will make sure the frequency response will always be equal on all mixing sessions. Our ears pick up frequency balance extremely differently at different volume levels if you did not know.