This works better http://www.nch.com.au/switch/index.html to batch covert between formats. It will save in the same source folder and convert to same channels stereo or mono. You can use FastCopy to copy selected files and folder to another drive. So you can copy all but wma.

Make sure you use VLC or Media PlayerX as the default player on Mac to play the RealTrack/Drums and styles demos that are in wma format or convert the to m4a with http://www.nch.com.au/switch/index.html

X:\bb\RealTracks\Data
X:\bb\RealTracks - Demos (if you are running the main app from the OS drive then convert that folder in /Applications/Band-in-a-Box/RealTracks - Demos).

This way the Audiophile drive will work on both Win or Mac.
Mac will need NTFS write enabled to write to the drive, you only need this to create usertrack or loops as it need to create the .bt1 beat files.