Sound Blaster Pro and Aztech Labs Sound Galaxy NX Pro should work.
You will, however, lose the ability to use the CD-ROM interface (this is what the extra connectors on the bus is used for).

However, why would you want to run a 16-bit (stereo) card in an XT?
No games from that era supported stereo sound, let alone had sound support (I'm now referring to the IBM PC XT and its clones). It wasn't until around 1987 when the Adlib sound card was introduced to the market.

to function as adlib.
There sb sb 16 that function as, and therefore, as adlib

You can perhaps lookout for 8-bit Sound Blaster clones like the Sound Galaxy BX, BXII or NXII cards or even something like the Toptek Golden Sound or Media Vision Thunder Board (there were many more clones made).

I don't see why a SB16 would not word in a true 8bit slot.
Just make sure you set the high-DMA the same as the low DMA.

http://www.amoretro.de/2012/11/aztech-sound-g … -pro-extra.html
Bottom image, you can see a piece of paper fully covering the 16bit part.
You can try with a SB16..

Perhaps my memory is a bit faulty, but I think I once read a post here about a SB16, which was installed in a PC/XT.
I don't remmeber the model, though. Was it a 1770 or a 2230 ? Sorry, can't remember anymore. 16Bit DMA maybe doesn't work there, though.
Except on some Vibra models, perhaps (2x 8bit) ? Sorry again, my experience about XTs is still sketchy. 😊

Edit: Sorry, my response was a bit too late. Haven't seen your answer (was typing).. 😅

A problem could be that the setup software can't run on an XT.

by acting as adlib not need to run the setup

It'd probable be safest to get a non-PNP card if you want to avoid any possibility of software incompatibility.

They tend to be more expensive and harder to find, but they are out there. Look for lots of jumpers for selecting DMA\DRQ, IRQ and address. They also frequently have volume dials... so that's an easier thing to look for.

I've thought about adding a sound card to my (modified) IBM 5150 a few times, but in the end the system just isn't fast enough and doesn't have enough memory to really be suitable for a lot of the games that would make good use of a soundcard. Basic Adlib support is probably useful, sure... but you have to remember that Adlib cards are from the 386 era, so its not unreasonable to expect games that used cutting edge (for the time) sound technology to also need better CPUs and more memory. Also, limited expansion card support is a deal breaker with a lot of PC\XT systems. I'd have to give up memory+gameport, hard drive, floppy drive or my 286 upgrade to put in a sound card. Without switching to a totally non-IBM-PC-era floppy+MFM controller (which would certainly render the historically interesting data on the original hard drive inaccessible), there's no way to add a sound card.

If your system has more flexibility, you could certainly try playing some early Adlib games with any 8 or 16bit card that has an OPL3 (or OPL2 for that matter), but don't expect stellar performance in all titles, even if it does work. Also, you'll probably want a VGA card too, or at the very least EGA.

I have successfully used a SB16 CT2770 on an XT motherboard with DOS 5.0

Probably the greatest benefit is to run the PC speaker through the sound card, it sounds a LOT better than a tinny beeper.
I had Lemmings working fine with Stereo sound, but even at 10mhz the game is dog slow.
I would say some earlier adventure games might work best through the sound card as they don't generally need a powerful computer.

Realistically XT's suit the earliest pc games to the mid 80's, after that You need something more powerful for most software.

I have testet Sound Blaster 16 - CT4170 and CT2260 on 8bit ISA on an Amstrad PPC640 - NEC v30. Works fine.
Using UNISOUND to initialize.
I have a video on that her: https://youtu.be/1tC3t2kLSpI

Yamaha YMF71x cards work in 8 bit slots as long as DMA0 is not selected (and IRQs only on 16bit side), the card will start misbehaving then.

When using a 16-bit sound card in an 8-bit slot, remember that DMA channel 0 was used internally on the PC/XT and is only available on the 16-bit extension, although DMA channel 0 is an 8-bit channel. So the only DMA channels that work in an 8-bit slot are 1 and 3 (and 2 of course, but that one is occupied by the floppy controller and usually not available on sound cards).

What about WSS (Windows Sound System) and Pro Audio Spectrum cards?
They do work different, use less of the usual ISA resources (IRQ/DMA).

WSS works off 8bit IO and DMA and will work fine in 8bit slot as long as IRQ and DMA channels present only on 16bit side are not used.