I see a similar issue now, on 26 Dec 2018.
Pacman finds 5 updates:
btrfs-progs-4.19.1-1 filesystem-2018.12-2 graphite-1:1.3.13-1 grep-3.3-1 sed-4.7-1
Pamac 22.214.171.124 on the other hand says “Your system is up-to-date”. There is no fresh [PAMAC] entry in pacman.log.
Can someone look into that?
This might have nothing to do with software or configuration. I assume your externtal sound card is USB connected, and that your PC powers down all USB devices during S3 (suspend). In that case the pop is just a result of power coming back to the electronics in your USB device.
You can test this by changing a BIOS setting to keep USB devices powered up. Many recent motherboards support that option.
Alternatively, you might try another sound card which handles power transients better. I have an Asus Xonar U3 and the pop is barely noticeable.