Yeah, I was actually wrong about that. The voice with OCT 0 FNS 0 does play fine.
Here's an interesting pickle for DSF: Mame Italia just sent in a dump of the Naomi game "Toy Fighter", and while the game itself doesn't run yet in MAME, the game's test menu does, including the sound test. After adjusting the AICA to address samples throughout 8 MB of RAM instead of 2 the tunes sound pretty good. So I'm willing to tweek the spec so there's 8 MB of RAM instead of 2. Highly Experimental won't like it, but I suspect Naomi may be a richer source of sequenced music than the DC anyway.