To the O/P, it is important to understand that sound levels are heard by humans on a logarithmic scale.
The decibel unit is the 'intensity' of the sound.
In practice, increasing a sound level by 10db will actually make it twice as loud as it was previously.
Reducing a sound level by 10db will halve the intensity of the sound.
Leaving -3.0db 'headroom' is somewhat of an 'industry standard' to allow for fine adjustments (filters, compressors, etc) without compromising the overall sound level.


BIAB & RB2025 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones