I just did a fresh install of Artemis with Plasma KDE on an 11th Gen Intel NUC that had previously had different Linux’s installed. No issue with sound in the past. Today, however, when I setup the sound to HDMI 5.1 and tired to test the sound I noticed that right was left and left was right for front and rear speakers. Never had this issue before even with EOS or Archlinux.
Thanks for that reference link. I did get this solved, but I don’t know what was really wrong. I reset the PC, TV, and A/V receiver and made sure there was no setting like Multi-channel Stereo on on the AVR.
At that point Plasma KDE Audio settings test and command “speaker-test” both had all 5 speakers correct and the LFE put noise in the sub-woofer.
Oops? I’d thought that @nate’s post above did bring about a solution, but then again, perhaps I didn’t read your post well enough?! - Sorry, maybe I’m getting too old for this.