Using a YMF724 (also tested with 744), SB-Link cable with S-IRQ and PC/PCI enabled, King's Quest VI with latest AUDBLAST.DRV doesn't work properly.
The narration cuts off, the screen goes black, and then narration stops working.
If an older AUDBLAST.DRV is used, it's somewhat better, though the screen goes black momentarily, but it does recover and the narration continues.
I got a similar result with Thunderboard selected for the narration. I did get Thunderboard working better though by disabling ACPI, assigning an IRQ in the BIOS to the card, and reserving the IRQ for Legacy ISA. No more black screens and it seems to be working fine (though I will have to play longer to know for sure).
The narration is of noticeable lesser quality with either thunderboard or the old audblast.drv.
EDIT: It works perfectly.
I installed a real SB16 and still had issues, so I installed the SB16 drivers, and it ran fine, albeit with an older audblast.drv. I removed all the strings from autoexec related to SB16 except for the modified SET BLASTER line it had placed there, re-installed the Yamaha card, and it works flawlessly. So KQVI runs fine with SB-Link.
But the most important thing you need to do after copying the older audblast.drv is described here:
Diagonsing and Fixing DOS Games - King's Quest VI and the Sound Blaster 16
Increase the audio buffer size for smoother speech. First, make
sure you're using a boot disk to free up plenty of memory. Ed […]
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Increase the audio buffer size for smoother speech. First, make
sure you're using a boot disk to free up plenty of memory. Edit the
RESOURCE.CFG file in the C:\SIERRA\KQ6CD> directory. The default is
"AudioSize = 8K". Increase the size to "24K" for smoother speech with
more free memory. Note that this is for KQ6 running under DOS (rather than Windows.)
I set mine to 16K, and you can read the blog post to understand why (I was afterall trying to get it to work with an original SB16 DSP 4.11 as well).
Now unfortunately, the 5871 byte Audblast.drv seems to downsample to 8-bit. The author, who goes by Great Hierophant on this forum, describes three versions of the file:
King’s Quest VI, Version 1.000
AUDBLAST.DRV 09/10/1992, 5,871 Bytes
King’s Quest VI CD, Version 1.000
AUDBLAST.DRV 04/26/1993, 7,670 Bytes
King’s Quest VI CD, Version 1.034
AUDBLAST.DRV 07/16/1993, 8,749 Bytes
I've PM'd him to ask for a copy of the 7670 Byte version.
EDIT #2:
While the above fix was indeed pertinent to getting KQ6VI to work with my SB16 DSP4.11, it in fact had nothing to do with the Yamaha cards.
In fact, what makes KQ6VI work properly is having DSDMA load at startup. I had inadvertently enabled it when I was playing with autoexec.bat in-between card swaps. So I'm not sure if having SB-Link and DSDMA together is the solution, or perhaps it can work with only DSDMA itself, but the fact is the game does work perfectly with these cards.