I just upgraded my desktop to the new AMD Ryzen 3900X and on that occasion also replaced my decade (!) old GPU with a recent Nvidia RTX 2060. Initially I couldn't get it to output audio to the speakers in my monitor (connected using DisplayPort).
pavucontrol to switch of the other
HD-Audio Generic device did the trick.
After some more research I also discovered volumeiconcache, a small app that shows a volume control in the system tray (i3 in my case). It can be configured to open an external mixer on click (
pavucontrol) and can also be directly used to control the volume by scrolling. Awesome!