Day's news.

I could create a Music/sound Rom with your ADPCM-A encoder tool and svrom.lua (thanks freem). I test and have good results.

Now I need to add the adpcm-b to my rom for the looping flag and test the Sound off.

I read some doc
https://wiki.neogeodev.org/index.php?title=YM2610_ASM_defines
https://wiki.neogeodev.org/index.php?title=YM2610_registers
and SOUND_STOP equ $D00046 ;byte

I think I don't try to change your z80 code but use the flag in adpcm-B for looping. Something like send 0x02 to PB_FLAG.