Dolby reference level (for movie theaters) is the volume control setting that produces 105 dB output from a 0dBFs (digital full scale) test tone on each channel. Or, more typically in home theaters, when -30 dBFs pink noise produces 75 dB output from each speaker.
It's very loud in the home theater environment, probably 6 to 10 dB louder than most people listen to movie soundtracks.
