How to totally remove HDMI audio (not just disable)?

While I only have this issue in one game, it is very irritating.

The way I have my monitor set up may be somewhat unusual, but it works well and hasn’t had this problem until I got my new PC back in march.

I use a 5 input HDMI switch due to having so many input devices, but i never use HDMI audio on any of my devices. For my main audio, I use a USB DAC (SMSL M3).

For some reason, when I switch inputs on my HDMI switch, the computer audio very briefly stops seeing my DAC and for that fraction of a second tried to switch the audio to the HDMI output. If I quickly change inputs when I want to check another device while I’m in my game, it then introduces loads of loud crackling and popping all over both channels, but randomly whenever there is loud audio in the game. To get rid of this, I tend to need to restart the game and computer. Things that make me certain it is related to the HDMI audio drivers is that if I use DVI - DVI to my monitor, then switch inputs on my monitor, I never get this issue. I also don’t get this crackling from the motherboard audio. It seems to be a digital HDMI audio interfering with USB audio, which is odd.

Given using DVI can sort it out which means a cable that can’t carry audio stops the problem, it must be the fact that HDMI carries audio can introduce it. There must be another way, but i actually already know that if there was such a thing as an HDMI cable that didn’t carry audio, my problem would be gone. If there was some way of totally removing the HDMI audio drivers so my PC can never even attempt to switch to a different audio device, then I think I will no longer have this issue. I’d thought of something that I was sure would fix it and that was a DVI to HDMI cable. But the graphics card somehow sends audio through the DVI port too!

I will also mention that my motherboard is the Asus Prime B550M-A Wi-Fi. This apparently is known to have issues with USB and crackling audio which a BIOS update apparently fixes. However, the audio is fine all the time other than in this game when I switch input / come out of full screen or something like that. So I’m not sure if it is related to the BIOS problem. There have been several BIOS updates, but I don’t understand how I update them.

Would appreciate some help.

Thanks.