I wonder if you're having speed issues - can you slow that bad boy down a bit and see if it helps? Maybe disable the cache in the BIOS or something?

Since my first post I tried both of the troublesome games under Windows 95. Sim City 2000 gives me sound there, and the setup program detected my sound card where it had not done so in DOS. Settlers still doesn't detect anything. Curiously, when I reboot in DOS 6 and run the same working install of Sim City 2000 from my Win95 partition there's no digital sound. MIDI still works (always did).

Just tried disabling both L1 & L2 and it did not make a difference to either game. . . well, other than loading times.

Sim City's installer is complaining about not having 4MB of memory, and its diagnostic program is showing my total extended memory as negative - presumably because the installed 128MB is confusing it. I should have a 32MB stick I can swap for so I'll try that - I figure t's possible the game thinks I don't have enough memory for it to load sound.

Edit: Well THAT didn't help. 32MB of memory shows up as "You have -32768K of memory" . . . real smart Maxis, signed int 16 to store that huh. Tried to fiddle with EMM386 switches to limit memory further but it did not seem to work.

Doom is not working in DOS either - same settings work under Windows 95. Think I might be ready to give up on this card.

It sounds to me like something's going wrong in the plug-and-play initialization, if it's not working with Doom on DOS. I have one of those in a 486DX4 VLB machine, and it works fine with Doom there.

Do you have your config.sys and autoexec.bat handy, along with any BIOS settings that might be relevant to PnP?

So I've had another play with this. It seems the main issue is that I had removed the loading of the main DOS driver from autoexec.bat (!) ...there were reasons for this which I will come to. What confused me I think is the number of games that were able to work and provide sound without it - sometimes digital, more often just midi.

With the driver running there is another issue - namely that digital audio is incredibly loud and the mixer app will not adjust it at all. Even at lowest output digital sound is loud to the point of crackling distortion. In fact as soon as the driver loads during DOS startup the output is a mass of loud pink noise. I think this is why I removed the "driver", which I've only recently realised was actually important. Considering how much worked without it I feel partly justified in that confusion 😜

So now more things are working, eventually. The default IRQ 5 was not working right, but IRQ 7 was alright. I've check the BIOS and it seems I had already disabled as much as possible in there in terms of PnP / IRQ sharing. I now have things set for IRQ 7 dedicated to ISA, and the parallel port that would normally use IRQ 7 is disabled. I have sound, but also a collection of other weird issues.

Rise of the Triad has crazy loud sound that is distorting like mad even with the digital sound turned all the way down in the mixer. Dune 2 has no Midi sound until it tries to play a digital sample, at which point MIDI starts playing. Then after a while and too many digital sounds playing the sound crackles and goes silent for a few seconds, before starting up again. Doom sound on the other hand seems completely normal.

It's late so I'm going to stop for now. Too many different random issues 🤣.