The calibrated volume at which film soundtracks are mixed — hitting it cleanly is a real test of a cinema system's headroom.
Cinema soundtracks are mixed to a defined loudness standard so that "0dB" on a calibrated processor reproduces the film as the mixer heard it. At reference level, dialogue sits around 85dB and peaks can hit 105dB, with the subwoofer channel reaching 115dB. Most people watch 5–10dB below reference at home, but a system that can hit it cleanly — without compression, strain or a subwoofer running out of travel — is the mark of real headroom.
Reaching it depends on speaker sensitivity, amplifier power and, crucially, subwoofer capability. It's why serious theatres over-spec the bass.