Correct, EmuTOS is lacking DSP XBios functions: http://sourceforge.net/p/emutos/code/ci ... status.txt
There are 32 of them and they also interface with the sound matrix so it's quite a bit of work.
Reason why it may have worked earlier, could be that EmuTOS didn't return correct error code for unimplemented
functions, but I'm not sure how long ago that was and whether it concerned also XBios part of OS.
EDIT: added link to EmuTOS status doc.