On impulse tracker was the option “centralise sample” it meaned that it changes the 0db line on the average of positive and negative oscillations of the wave sound. Like this you can get more power with normalisation… And your compressor works much better
Some samples are not centered (only positive movments) it happends often with old movies samples or heavy formant filterd synths…
Can we do this?
I tried to find the answer in the FAQs but i dont find (thanks to my awfull english)
There is a button for that to the right of the normalize button in the sample editor (“Auto DC offset”, ctrl + D by default). There is also a “DC offset” effect 
i m so stupiiiiiid!!!
i thought dc offset was totally other thing!! looool
Kick me!!!