SB PRO drivers are a headache even with real hardware somehow. Windows 3.1 integrated Sound Blaster 1.5 drivers are rock solid even with clone cards. Sound Blaster 16 drivers are hard to set up but ok to use. But somehow Sound Blaster PRO 1.0 drivers do not exist. And Sound Blaster PRO 2.0 drivers are buggy/picky. Maybe someone can shed a light to that. Even Windows 3.00 Multimedia Version has better Sound Blaster drivers.

I think same. There are a few at vogonsdrivers.com as well.

What's notable about this time frame is that the SB 1.x, 2.x and Pro models had been supported by ordinary, old Windows 3.0 already.
The earliest SB drivers were shipped as a simple DLL file (sndblst.dll), which only a few applications had supported.

After Windows 3.0 MME or 3.1 was released, it had been abandoned.
Creative disencouraged to use that DLL in further application releases.

So there was a switch of some kind happening. From sndblst.dll to real Windows drivers.
Maybe that also was a time of re-writes of Sound Blaster drivers, resulting in bugs or stability issues.

Considering that the SB Pro was the flag-ship model during the trasitional time, the most complex model with a shortlived mixer chip,
it might explain why its driver was most buggy.

But that's just an idea.

There also were builds of Windows 3.0 MME that shipped with SB Pro drivers..
If they work stable, maybe Windows 3.1 can be installed as an upgrade over 3.0 MME?

Yes Windows 3.00 MMW sound drivers can be used in 3.1. Have not used them long enough to notice any critical failure or bug.

I don't know about 86box, but SBP2WU.EXE worked fine for me in DOSBox.

Eh? Never had issues with Win 3.1 SBPro driver install. IIRC you install it in DOS first, then go to the WIN folder inside the SBPRO directory on your HDD and run the exe in there from within Windows.

I ran into similar issues with older sound card drivers, especially with emulators like 86Box. What worked for me was tracking down some vintage driver sets on Archive.org. They sometimes have working versions of old drivers that aren't available elsewhere. If you’re still having trouble, try finding some on forums dedicated to retro computing; someone might have an archived, stable version.

The attached disk image is a stock SoundBlaster Pro 2 driver disk. I tested it with my CT1600 Rev. 07 card. I installed the drivers in MS-DOS first which created a C:\SBPRO\WIN31 folder containing the needed OEMSETUP.INF for Windows 3.11/WfW. I started WfW, pointed it to this folder, and installed all of the devices available then restarted Windows - now sound is working great in both DOS and WfW 3.11 with the SB Pro 2.

Also attached a copy of the C:\SBPRO folder in case it's helpful for anyone that doesn't want to install the drivers first, e.g. to grab just the Windows drivers.

I found other drivers online, but with issues. One of them required two disks which is a hassle if you only have one disk. Another copy from Archive.org seemed corrupted and I got CRC errors during installation. The attached drivers and files should be perfect.