It’s fixed! I changed the disk operation back to AHCI in the BIOS. The audio crackle/pop returned. I uninstalled Intel RST and then installed the drivers for the EVO 970 Plus. Audio issue resolved. I reinstalled Intel RST to see if that would cause the audio issue to return. No change. Audio is working correctly.
Hello. I recently bought a used 5590 online and just completed a fresh Windows 10 install. Everything worked great with the exception of the audio. Anytime I would change the volume or play anything with sound, it would pop and crack. I tried uninstalling/reinstalling the Realtek drivers only to have the same problem. To make a long story short, I found another individual online—with the same issue—who contacted Pro Support and he found a workaround by changing the Disk operation mode in the BIOS from AHCI to Raid on. I can confirm that this works—at least for me. However, I would like to change it back to AHCI because I’m unable to use my Samsung Magician software to manage my EVO 970. Does anyone know anything about this issue or if it’ll be addressed in a future software update? The individual that I’m referencing posted his solution over 1yr ago so it doesn’t seem like it’s a high priority fix. Also, It’s interesting that support knows about the issue and it still remains unchanged. Thanks for any help.    
Latitude 5590 Sound crackle/pop