Diagnosis
This is the expected performance of the monitor's 2W internal speakers. They are designed for basic audio, not for gaming or media depth. The perceived lack of bass is a physical limitation of the small speaker drivers.
How to Fix It
Use the monitor's audio output for quality sound. Connect external speakers or a headset to the 3.5mm Audio Out jack on the rear I/O panel. This will bypass the internal speakers completely. Configure your PC or console to output audio via HDMI/DisplayPort as normal.
If That Didn't Work
If you must use the internal speakers, you can adjust their profile. Press the joystick for the OSD. Navigate to Sound > Treble and reduce it to 2. Navigate to Sound > Bass and increase it to 8. Navigate to Sound > Audio and select 'Game' or 'Movie' mode instead of 'Standard'.
Heads Up
The monitor's 'TreVolo' audio branding refers to the tuning software, not a subwoofer. Do not expect significant low-frequency response. For the best experience, BenQ intended the Audio Out jack to be used with the included, compatible speaker set or a user's own high-quality audio solution.