Are you saying, without any doubt in your mind, that it would be infeasable to carry over the sequencing, but render it with new samples?
You're right, I was jumping to conclusions too quick. It would be possible since the spu and cpu are separate on most consoles. This is to prevent slowdown effecting music. It is quite possible the emulated cpu is sending info to a rewritten DS spu interface class. That would provide extra spu ram, since it is not emulated. In addition, you can add cart space via emulation, so there is no reason they can't be stored. Also, I would imagine since the spu handes sound ram, they could be whole new formats, or even pointers to outside of rom data.