Per Greg Giametta,

At the current time, Sampletank can import AKAI s1000/s3000 samples
ONLY. What this means is that, you cannot import WAVE or AIFF data into Sampletank and play it. This product uses a proprietary format for it's sample data. Which is why it gives you such a large sample library to get you started on your way.
Development for WAVE and AIFF usage is almost complete and they hope to issue this new function in the next update which is about 8 weeks away. This update will be applied to the already handy ST convertor that currently handles your AKAI samples. It also will self map your new samples... saving the customer from the pain staking process of "mapping a sample".