Roland BOSS RC-30 Looper Station http://www.bossus.com/gear/productdetails.php?ProductId=1160 offers connection to computer with USB. It alowes download wav files stored on device and upload new files from computer.
You can edit it manually using Finder or any such tool, but you need to convert files to WAV and name it according patch number.
This editor simplify this prices to easy drag and drop any file, converts it automatically and place it to proper place.
Program is very simple but functional.
See demo here https://www.youtube.com/watch?v=CWte3UDHHpQ