I have found a beginning of an explanation in another vogons thread.

Note that there are two methods to get digital CD audio under Win9x. One is to use a SPDIF cable which connects the digital audio pins on the CD-ROM drive to the corresponding set of pins on the sound card. This works fine with either VxD or WDM drivers. However, some PCI sound cards don't have the pins for a digital CD audio connection. Also, these pins are very rarely present on ISA sound cards.

The other way is to use the internal data bus of the computer to transfer digital CD audio. This doesn't require any extra cables but (depending on the sound card) you often need to use WDM drivers, which are suboptimal under Win9x as they can reduce game compatibility. Lastly, you need to activate the "Enable Digital CD Audio" checkbox under the Device Manager entry for your CD-ROM drive in order for this to work.

I am interested in enabling the second case which user @Joseph_Joestar calls "internal data bus". It seems I need to install a WDM driver for my Sound Blaster 16 but I cannot find any. It could be that the card is not capable of WDM? I found such drivers for the Sound Blaster Live on vogons here.

fabiensanglard wrote on 2025-10-12, 07:53:

I have installed Windows 98 on my 1997 PC and the option to have audio CD playback handled by Windows is grayed out (see screens […]
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I have installed Windows 98 on my 1997 PC and the option to have audio CD playback handled by Windows is grayed out (see screenshot).

The attachment cd_cannot_play_digital.png is no longer available

1. I have not connected the audio cable from the CD-ROM to the Sound Blaster 16. I assumed, since the CD-ROM is connected to an IDE port, this would not be needed.
2. I have read on other thread that I may have to install a WDM driver. But is it a driver for the CD-ROM or the sound card?
3. How can I check if the driver is WDM or VxD?
4. If I find the WDM driver, do I still need to connect the CD-ROM to the Sound Blaster via the audio cable?
5. I have installed WinAmp 5.35, the latest version compatible with Windows 98 AFAIK. It is able to play audio CD without any driver. How come Windows can't do it then? How is Winamp doing it?
6. Am I misunderstanding this setting? I assumed it was to allow Windows to do like Winamp and playback audio CD from the IDE interface. But it is just a setting so Windows uses the CD-ROM digital output instead of the analog one?

Windows 98SE supports digital CD audio via the IDE interface, meaning it's not necessary to use the audio cable to connect the CD-ROM drive to the sound card. The CPU can handle the digital to analog conversion for the sound card. However, there are a lot of caveats. There will be CPU overhead, which will I think be significant on a PC from 1997. Also, it (typically?) requires using the WDM drivers for the sound card, which will create a lot of compatibility problems.

1) That's right
2) sound card
3) check driver file name - if it's VXD, it will have extension .vxd, I think
4) No cable needed
5) That's strange!
6) No, I don't think you're misunderstanding it.

See this thread, if you haven't already (no solutions there, but might help): Sound Blaster 16 WDM Drivers (attached). Incompatible with DOS games. Please help.

I think it would be unusual on a PC of that era with a SB16 to use the IDE-interface digital audio instead of the analog audio cable. Can I ask if you have a particular reason why you want to do that? If you can even get working WDM drivers for a SB16, you should expect the SB16 to have severe problems with games.

There's also a question of whether your CD-ROM drive even supports it. I don't have any experience with that.

I've basically never used digital audio via IDE on anything earlier than a Pentium 4, as it always made more sense to just use the analog audio cable.

Edit: regarding Winamp, a quick search shows that Winamp may be capable of playing the digital audio via a plugin (perhaps this came pre-installed with the version you have?):

mentioned in passing here:
https://forums.anandtech.com/threads/enabling … in-98se.579252/
https://forums.anandtech.com/threads/how-do-y … dows-98.360436/

WDM drivers for Sound Blaster 16 exist. Windows Me and XP use them, for example.
"Sound Blaster 16" wasn't just our good old CT1740 of 1992,
but also was being implemented in Pentium III motherboard audio
and used in various PC emulators (such as Connectix Virtual PC for Mac).
So of course, there are WDM drivers for SB16. There might be one included in Windows 98SE, even. Sound Blaster 16 (WDM) or similar, not exactly sure right now.

Can I ask if you have a particular reason why you want to do that?

It makes the inside of the PC a mess. I hate this extra cable. I was hoping to be able to keep things tidy.

But the more I learn, and with the precious information you gave me, the more I think I will just add a cable (but maybe I'll go with a SPDIF). This is the Right Thing to Do.

1. It is how PC of that era were configured.
2. It won't mess up my games, which is the primary purpose.

fabiensanglard wrote on 2025-10-12, 18:26:

Can I ask if you have a particular reason why you want to do that?

It makes the inside of the PC a mess. I hate this extra cable. I was hoping to be able to keep things tidy.

Yeah, I know what you mean. The analog audio cables are often too short with an ISA sound card all the way in the bottom slot.

But it's very easy to make or buy a longer cable. I can't see exactly what connector options you have on your SB16, but on the CD-ROM end, it will just be a plain "dupont connector" (2.54 mm / 0.1 in pitch).

If you search Amazon for "dupont cable 4-pin" you can find a lot of options, and if need be, you can solder some wires together to get to your desired length and connector type. I'm not sure if there are detriments to the cable being too long, but in the recent past I always resort to making cables this way for the analog audio.

Audio cables can be hidden between the M/B and case, at least for some of the way if length becomes an issue.
Audio cables will also mean you give you CD-Audio audio in dos games if required.
BUT
How much do you really need CD-Audio? I've found majority of my collection don't use Redbook or I don't really miss the lack of music in the games that do.
That'll come down to personal choice of course.

chinny22 wrote on Yesterday, 01:03:

BUT
How much do you really need CD-Audio? I've found majority of my collection don't use Redbook or I don't really miss the lack of music in the games that do.
That'll come down to personal choice of course.

That's really dependent on what type of game you're into. A lot of my favorite games from 1996 - 1999 use redbook audio. Hard to imagine playing Half-Life without it! Also: Starsiege, Jedi Knight, Heavy Gear, more.

jh80 wrote on Yesterday, 01:35:

That's really dependent on what type of game you're into. A lot of my favorite games from 1996 - 1999 use redbook audio. Hard to imagine playing Half-Life without it! Also: Starsiege, Jedi Knight, Heavy Gear, more.

100% which is why I finished with

chinny22 wrote on Yesterday, 01:03:

That'll come down to personal choice of course.

Yes, there must be a WDM driver - I checked it and it works even in a virtual machine with a virtual ISA Sound Blaster 16 card:
https://www.elektroda.pl/rtvforum/viewtopic.p … 754080#17754080