Hmm. I have windows 8 and the first thing I did was install a free program called Classic Shell. That will give you a windows start menu on the desktop which windows 8 did away with (like, seriously, why?). I never run windows 8 using "tablet" mode - I always have it on desktop mode like windows 7. So, once you install classic shell (if that's the route you choose to go), go to the start menu and go to control panel, hardware and sound, then when you click sound you should see an icon showing hdmi out or whatever speakers you are using. You will right click that icon and choose "configure speakers". You should then have a choice between stereo, 5.1 or 7.1 sound. Choose the one that fits your setup, then test it. If sound comes out of all your speakers discretely, you're good to go. Hope that helps. If there are people who know how to do it without using classic shell, cool. That's the only way I know how to do it.