sampler loop end modulation

[greententacle]

hy guys,

I'm looking for a sampler where i can modulate (or midi cc) the loop endpoint when in loop mode, for that traditional kick roll/buildup.
i tried battery, Kontakt and geist2 so far, but they all mess up the attack in some way.
how do you do it?
iam in studio one 6 and vst.
tried the sampler in SO, doesn't allow automating the loop end.

thanks,