Currently the game has issues with various sound cards and speaker configurations as follows:
WORKAROUND: at present the workaround is to set speaker configuration to Stereo (2.0) or Quadraphonic (4.0) until the game is fixed.
There is a reply with links to many more folks having this problem and documenting it out on different sound cards here: https://www.gog.com/forum/the_witcher_3_wild_hunt/only_stereo_and_very_low_volume/post5
NOTE: This workaround only appears to work for some users and hardware configurations.
It did not work for me when output from either the Onboard RealTek Audio or the NVIDIA High Definition Audio via HDMI out from GTX 760
Original post follows:
Only Stereo and very low volume?
Windows itself knows I have a 7.1 Surround sound configuration. My other games seem to play out of all speakers correctly.
TW3, only the front left & right and at very low audio levels even when the game is set to 100% (at first I was hoping it was just the introductory cut-scenes).
This is unplayable, my email client message arrived sound is blaring when it plays while I have the receiver volume cranked enough to even hear the dialog during the opening cut scenes.
Version in game says 1.02 on the Main Menu
This is totally unplayable like this.
I normally have my sound on the receiver at an output of 10-12.
To even be able to hear the opening cut-scenes I've had to crank the volume to 44 on the receiver.
Having an email come in nearly knocked me out of my seat it was so loud.
I refuse to consider the only workaround to go into the windows control panel, and disable all windows sounds, and kill every other running application that might produce sound just so I don't risk blowing my speakers.
Sound works fine on my 5.1 system. Only running sound off my Asus Sabertooth 990fx Gen 3 mobo and I've got full 5.1 audio working extremely well. My sound is being pushed out by a Logitech 5500 system.