For users of Windows 8 and Windows 8.1, here's a problem you may encounter with your new PCs or when you upgrade your Windows versions.
Caveat Emptor: This tip will not solve all audio problems. It merely addresses a common one I've seen occur with several different PCs and I suspect many people will eventually encounter it.
The Problem
When playing audio (music, video, etc) you may hear the sounds as incredibly muffled or muted - as if you are hearing something in another room.
A Note on My Hardware Setup
Look at this image of my (JBL Creature) speakers below. Notice that there are only two speakers and the subwoofer.

When the Problem Started
I've seen this occur in three separate scenarios
In the uppgrade scenarios, the sound was working correctly before the upgrade.
How to Fix
Right-click on your Sound icon in the System tray and click Playback Devices.

The Sounds Control Panel will open. Under the Playback tab, right-click on the active speakers and click Configure Speakers.
This will launch the Speaker Setup wizard. Remember when I mentioned earlier that my speaker setup only had three components? As we see below 5.1 Surround is selected in Audio channels.

Select Stereo and click Next, Nexty, and Finish to get through the wizard.



Once the wizard is done, you should hear everything correctly in a few seconds.