If you are using PISCSI with your AKAI Sampler (I highly recommend it!) you can upload any .iso CD image files.
You will be able to attach the CD images  but this will not mount on the AKAI.

In order to make them work with an AKAI sampler, you will need to simply rename them to .hds files (Hard Disk images)

Here's a very simple command I have written to rename ALL .iso files in a folder to .hds, quite handy when you have a big list of files:

for f in *.iso; do mv -- "$f" "${f%.iso}.hds"; done