Function normalise_level 

pub fn normalise_level(c: &mut Converted, model: &mut Model) -> f64

Normalise a conversion’s output level like NAM plugins do, so every import plays at the same level (NORMALISED_LEVEL_DB) whatever level its model was captured at. Only G2 (after the pedal’s saturation) is scaled, so this is a pure volume change: the tone and the way the amp breaks up stay the same. Returns the gain applied, in dB.