Hi, I realise this may be an old topic, but I have just got my hands on HL2 and trying to play the game but as above when I run the game and go to the options, select 5.1 and save, then for some reason it keeps saying in the console screen "Speaker configuration has been changed to stereo speaker" and then the option shows 2 speakers again.
I have a 5.1 compatible sound card (ALC8768+ chipset), Windows 7 sound options definitely set to 5.1 and all speakers are testing and working correctly. I do not have any other game to test with, but movies definitely also play correctly with full surround.
Can anyone please help? I can't post images just yet, but the screenshots can be seen here: https://forums.overclockersclub.com/topic/208780-half_life-2-settings-wont-stay-on-51-sound-option/.