Sounds like you may have a defective NB take it back to the vendor where you got it.
Before you do that download the latest Driver from the Asus Download site for your NB, uninstall the current drivers reboot and install the latest available.
The Sub woofer is not in fact a LFE it is merely a bass speaker and all sound play's through it. With the latest drivers installed you should be able to turn down the volume of the Bass speaker enough that you can hear the Left and right speakers. Setting up the equalizer settings you can make is sound alright.
If not then you may have a hardware problems as I stated earlier take it back to Best Buy before you return time ends.
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro