[wirefall]

AFAIK SD 2.5 and higher works with an AMII. Last version of SDII is 2.83. The DSP is good for plugins for SDII, there were/are quite several. Rare to find now, as they were quite expensive, but delivered on floppies with key authorization. Most people sold the Macs with still the keys on the hard disks (but the buyer don't need them and so they are lost) and sold the floppies or sold them later separately (without left keys so they are useless as well, as it is a question of time, when you can't use the floppy itself as a key because of degrading).
Try SD 2.7 which should be available without authorization process.