Well, messing with the PAS16 drivers some more, I'm able to source the missing MVSOUND.SYS from another driver set, and that makes this card work a bit more.
- Load the PAS16 version of MVSOUND.SYS on config.sys, with the parameters as-is from the LW16 installer
- Use MVDIAG to set the volume level
Quick testing on Master of Magic shows that now the PAS16 music works, but no digital sounds. Setting from config.sys to enable SB emulation, I can then use the thunderboard for digital sounds. That kind of defeats the purpose though, considering the point is to use the MDR-401 and midi modules for music, and this card for digital sound effects and the CD-ROM drive interface. Neither of the two work with this hack (the lousy SB emulation doesn't count). But hey - the card is definitely less than 90% dead!
Still possibility to recover drivers fully if:
- Some miracle happens, like disks heal themselves or drivers appear from one of you humans to this thread or elsewhere on the internet
- Original owner finds the 3,5" disks and they're not as crunchy as the 5,25" disks were
- Original owner finds his hard drive and brings it here so I can poke around and recover the drivers from the original installation
The original seller pulled a rabbit out of his hat, and brought in today not only copies of the original 3,5" floppies - which worked, but also his original HDD - which also worked, and original manuals, plus another ISA CD-interface card, which he thought may or may not have been connected to the CD-ROM all along - and that also worked. I did yank the CD-ROM driver folder separately. For anyone interested, please find attached the original driver floppy contents.
In conclusion, the ACS LaserWave is now 100 % complete with drivers and original manuals, and the card is working. Well, mostly. Given that it seems to be a mediocre PAS16 clone, the card does seem to quirk out on some games, failing to produce other than SB emulator digital sound effects. PAS side music seems to work. Also the card's install.exe is way more happy than it was with the PAS16 sourced driver, and now the installer plays out test sounds without any hiccups. Seems to be 100% working clone PAS, which I guess means it is about 80% working in real-life terms.
For anyone looking for the LW16 drivers in the future: these are it, these are working drivers for the ACS LaserWave 16 ISA sound card.