It works fine, I can mount it with toast and even itunes will play the tracks. I'm wondering why they choose this format not a .img .dmg .iso or .toast and also what is a sound designer 2 file ?? When I google for it I get this
Sound Designer is a Macintosh application. Sound Designer II files store all sound samples in the data fork and all sound parameters in the resource fork. Sound Designer II was discontinued several years ago, and is no longer available. Quicktime should play the files. The Sd2f designation it typically the Macintosh creator code. The file extension is more often seen as .SD2.
I don't want to end up with 100 or so not compatible image files in a couple of years.