I dunno if you know the differences between Leonards YM2149-Player and Jims Saint ?!
To explain it :
Leonard uses an own format to play these previously "recorded" YM-Files so that he has nothing to do with that "real" emulation of the YM2149, except the frequencies and stuff ...
on the other hand SainT not just emulates the YM2149 but these assembler codes to let the emulated YM2149 play these sounds ...so it's a bit more difficult and I think it doesn't relay on the YM2149 emulation but on timer-emulation ... and this is one point, Jim told us on his homepage that he has to fix them to be more accurate ...