I have my speakers Logitech Z333 plugged in to my LG 32GK650F-B monitor, and when sound isn't active for a period of time it take some time before sound kicks in to the speakers. I notice slack notifications cut in half way in(the last end of a slack tone) or music cuts in late or delays when hitting play. It seems like there is some sort of sleep function after a minute of no sound. I had a similar problem with my built in intel sound output device and fixed it with this posting Annoying click/popping sound on Ubuntu 20.04.
I'm wondering if there is an equivalent setting for hdmi outputs. This is the pactl list short sinks output of the hdmi stereo:
9 alsa_output.pci-0000_01_00.1.hdmi-stereo module-alsa-card.c s16le 2ch 44100Hz RUNNING
In sound settings the output device is called HDMI/DisplayPort - TU104 HD Audio Controller
