Came to put my $0.02 into this thread. I got one of these a long long time ago from a scrap pile, was digging through my basement earlier in the week and happened upon it in a box. Rather, I happened upon it months ago, but really only got around to messing with it this past week.
Image below is after replacing quite a few capacitors that had gotten dented or otherwise ripped from their legs off the board. Also had to clean up the joints on quite a few of the surface-mount components near the wavetable header and almost considered doing the filter mod in the meantime... but more on that down the post a bit.

Some things to note about this board that are notable- For one, the solder pads on the through-hole parts, on the bottom side, are absolutely terrible. If you have your iron at any amount of a good temperature for ANYTHING ELSE, they will singe off in part or in full. In some cases I had to do a solder bridge to a nearby trace to get stuff reconnected and flood the through-hole with solder to keep the part in place with only the upper side anchoring it to the board.
I had an issue with the 719E-S on my card for some reason where I had to go back through and reflow every single pin twice to get it to work. Both of the main power filter caps near the slot edge were either heavily dented or broken off, and one of the output 16v 470uF caps looked like something tried to nip it open. I wish I took a picture before I fixed it, it was gnarly.
The caps I went with in this case were a couple of 0-hour Cheapo-Teapo 16v 470s that don't initially look matched, but definitely are. different plastic casings, yet measure pretty much the same on my meter, so in they go.
Also noticed I had to put 16v 47uF caps in place of the 10uF caps for the inputs to make the card run anywhere near stable. Could have been that all the other 10s I tried up to that point were problematic, but the increased capacitance doesn't seem to have harmed anything too much if at all. Given all the original capacitors on this board are G-Luxons from the late 90s, I'm definitely going to be adding a list from this card to the ever-growing Digikey cart and treat it to some fresh stock when money isn't as tight.
This is definitely a card for something running pure DOS if anything, or 9x/ME/NT4/2K/XP. WFW311 went absolutely bonkers with GDI errors after installing the yamaha reference drivers and such, to the point I had to restore the backup of my Windows folder from a couple weeks ago. It might be an incompatibility between this card and the WD7600 series chipset on my board there, but it just was not happy. Instead, after popping it into my PowerEdge 2300 running XP, it found the driver and worked without a hitch. Installing the Y-Station software off the win9x CD helped a bit, albeit with the volume controls doing weird things, but the 3D enable/disable seems to actually do something, so there's that. Also had problems with the gameport on this card on the 386 as well, even properly configured... and yet, on the PowerEdge with XP, works just fine. Also another reason why I believe there's a compatibility issue.
Overall I like the audio without the filter mod so I'm not going to do that just yet, not until I get my hands on a couple wavetable cards to do some comparisons with... This is one of the only two cards I have with such a header (the other being a TB Santa Cruz card) and if I can help it, both are going to get the same card, and probably something from Serdaco in the end. Am I right in assuming that the low-pass filter mod also affects the waveout sound as well? if so, I may want to stray away from that entirely anyway.
Below are a few recorded 320K MP3 samples of the audio from my card post-repair, and some control recordings from a couple other cards. I chose Dune for this, as the Arrakeen Palace bgm is complex enough to really tell the difference. There's also a point 10 seconds in where some cards in my collection (namely my SB16 Value CT2770 every time, compared to my CT1740 and CT1750 which do not, nor does my Awe64 Value) will sometimes miss a note and set off a wrong instrument, which seems to happen here only after ymersion is disabled. Interestingly this missing note seems to be a random occurrence on this card, but I've only see it happen on OPL3 cores baked into other chips thus far. Trying to get my hands on a CMI8330 card to test that out later.
The attachment OPL3SA3-Dune-Arrakeen1.mp3 is no longer available
The attachment OPL3SA3-noymersion-Dune-Arrakeen2.mp3 is no longer available
The attachment CT2770-Dune-Arrakeen3.mp3 is no longer available
The attachment CT1740-Dune-Arrakeen4.mp3 is no longer available
All in all, good card. VERY good card, so long as you have a proper usage case for it.
(Edit: Added CT2770 and CT1740 control recordings for clarity.)