I made the same findings. See
#1442 at the end of the postings and
mrbumpy409/GeneralUser-GS#8

I see and your findings will help. Also, I notice the same issue in FluidSynth 2.4.1 but not 2.4.0, and wonder what changed in 2.4.1 to cause this

@klerg Any mails that you send to me privately will now be automatically moved to my spam folder. Fluidsynth is a project that I do in my spare time. Because of that, it's up to my sole, personal and completely biased decision, which issues to look into and esp. when to do so. I appreciate your (and anybody's) bug hunting. Yet you will learn, that it is highly counterproductive to ask for status updates every few days.

No need for this as I hardly send any mails to you and will be doing the same thing as well then. I also use Fluidsynth in my spare time like many. Sure, I never told you how, when, or where to look into any issue, and that is the way every dev goes about looking to fix a bug. The best way to appreciate it is to try and get rid of any bug. Yes, this is the only part I agree with you as it does not help and I'm not going to do that

I am currently looking into this. I was able to reproduce with on Windows with dsound and wasapi audio drivers, but using waveout doesn't cause any problems. I was also able to reproduce this on Linux using sdl2, but using alsa does not cause the issue.
The audio stops because the gain suddenly becomes very high. I still need to understand why.

Thank you very much.
Please see my recent post at #1442 at the end of the postings where I found that in particular for the recommended reverb and chorus settings of mrbumpy409 the issue is permanent for dsound and wasapi. May be this observation helps to find the cause. Again, thanks a lot.

I think I found it. A tiny oversight from #1432. #1476 fixes the problem for me on Linux. I'll verify later that it fixes it on Windows as well and then release it together with 2.4.3. Thanks for the report!

Sure, glad you were able to find the issue. To verify it later, does this mean we get some binaries for Windows to test it and see if it works before 2.4.3 is released ?

I can confirm that the issue is resolved in 2.4.3 on Windows. The drivers which we use (dsound, wasapi (+ exclusive), portaudio + ASIO, Jack) all sound fine. No crack can be heard. Excellent job. Thanks a lot.

That is great to hear it works in 2.4.3 with Windows. But what is exclusive driver, all I get is dsound, wasapi, and waveout. How to use portaudio, ASIO, and Jack in Windows ?

Here are answers to your questions:

Creating the audio divers, see
https://www.fluidsynth.org/api/CreatingAudioDriver.html

WASAPI exclusive, see
https://www.fluidsynth.org/api/settings_audio.html
You need to set "audio.wasapi.exclusive-mode"

ASIO, see
https://www.steinberg.net/developers/
Using ASIO you need to sign a contract with Steinberg. A contract draft is included in the package.

Building portaudio with ASIO, see
https://portaudio.com/docs/v19-doxydocs/compile_windows_asio_msvc.html

I see, so for Wasapi exclusive just have to set "audio.wasapi.exclusive-mode" but jack, portaudio, and ASIO need to compile from source ?