when resampling set your master level to 0dB.
beware though, you may clip.. however scaling the volume back on the mixer is a finer adjustment than knocking back a whole 6 dB.
for resampling single hits,if you haven't used velocity switching layers. you can use the 16 levels velocity to sample at a few different levels...then choose the one that doesn't seem to clip...
I do this when I have layered up a pad but don't want to keep loading 3-4 samples to get the same composite drum sound in another kit....kinda like layer finalizing.