@mima @Pawlicker The so-called standalone ADPCM channel is called
#ADPCM-B by some technical documents, while the RSS is called
#ADPCM-A. That Japanese doc you linked says it retains the 6 rhythm channels (the RSS), however it warns that the left/right panning has been reversed (unsure if this only affects the RSS or if it also affects the FM channels). It also says that soundcard handles PCM sound, so I wonder if it can support the
#P86DRV &
#PPZ8 PCM drivers used by some
#PC98 VNs like
#Grounseed &
#EVEBurstError (as superior substitutes for the missing ADPCM-B). While ADPCM-B only supported hard left & right panning, the external PCM in the
#PC-9801-86 card had 127 levels of panning for each side (when using the PPZ8 driver, this got reduced to 4 levels of panning for each of 8 virtual PCM channels provided by the driver's software mixer).