Linux Mint

Sounds odd, but you could try putting a double adapter in the output of the sound card and add a pair of headphones. It sounds like the sound card sleeps when not in use and the speakers don't like it. (The impedance goes away. Headphones force it to always be relatively low.)

Or treat yourself to a usb mic with a headphone output and use that output with your speakers to bypass the weird sound issue.

If bored try a Fedora iso with ventoy to see if other distros have the same issue with your hardware.

Sounds like -something- is slowly cranking up the input gain trying to find a signal that's above the noise floor.

Some apps also have settings that will let you do things like that ... Audacious being one. ('Effects' section in 'Output' menu. It also has a 'Silence removal' setting that might help. ). You might try listening via different apps to see if the one you're using could be doing it.

Analog amplified speakers?

Could be power saving by pulse. I haven't needed to disable it in awhile though. When power save kicks in you'll get noise.

For example, to disable on an Intel card:

#/etc/modprobe.d/audio_disable_powersave.conf options snd_hda_intel power_save=0

They switched from pulseaudio to some new sound driver with v. 22. I would search and/or ask on the Mint forums, there's almost always solutions on there.

are you using pipewire? if yes, you might have been on the right track turning off powersave mode - only that you should turn it off via your pipewire session manager. most likely that would be wireplumber:

in

/usr/share/wireplumber/main.lua.d/50-alsa-config-lua

the following line should look like this

["session.suspend-timeout-seconds"] = 0

0 being the value to disable soundcard suspension