Windows 3.1 does indeed support multimedia in Standard-Mode, except..
Except if manufacturer provides the drivers as VXDs only (286 needs *.DRV drivers).
The same is true to video drivers of high resolution/colour depth.
Some of them do ship with drivers for 386 Enhanced-Mode only.
The sound drivers that come with Windows 3.1x do support Standard-Mode.
You can select the SB 1.5 driver, for example.
By the way: Windows 3.0 with Multimedia Extensions 1.0 had Sound Blaster drivers, too.
These drivers included SB 2.0, SB Pro 1 and SB16.
All of them ran in Standard-Mode, too, which is notable.
So maybe you can use 3.0 MME and upgrade to 3.1x?
Later Creative drivers (later SB16 drivers) required 386 Enhanced-Mode to run,AFAIK.
PS: Back in the 90s I had a PAS16 soundcard in my 286.
It had Standard-Mode friendly drivers for Windows 3.1x.
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