Solved the issues with FastATA & IDE-Fix drivers, both coexists now without conflicts.
I found another way to play from SCSI bus.......
Installing the CDDA-FileSystem (Aminet) and making a separate Mountlist for each drive (only mounted when needed), the AmigaOS recognizes each track like an .iff file. So, it's possible to play directly from AMPlifier & other players.
I maked all tests without any audio cable connected on the drives.