Looked over the manual, especially the "Studio" section, and I find it rather unimpressive (lacking).
Anyways I could not find a place that states what key the drum samples are in?
Some samples, when loaded in Studio, can be tweaked with "Pitch" and some with "Tune", not sure of the inconsistency, but what is the center reference point (Key)?
If I was to venture a cautious guess, I would say "C".