it only uses sfz files that call up flac files for their sounds.
the sfz files have variations in them thus not having to have 50 flac files each at a different velocity.
at the end of this video you can see where I change the sfz files and not the flac files to change the hi hats.
the hi hat in session drummer is one of those instruments that have 2 files in one,open hat and closed hat.
thus if it were .wav there would need to be a slew of files.
http://www.youtube.com/watch?v=TjZS61Wg-XY I can only guess the pointers are there for the drag and drop feature.
which you are able to drag .wav samples in and drop them on each instrument of the kit.