No subwoofer output when playing stereo files

[nhelder]

Hi, all~

I'm running in to an issue specifically with stereo playback - namely, the subwoofer channel appears to be missing.

I can play DTS/AC3 audio tracks and get subwoofer output fine, but when playing a ALAC or LAME encoded audio file (.m4a/.mp3), the subwoofer remains silent...

...does anyone have any idea what might be causing this?

Thanks in advance,

- Nathan


Additional background:

Dell OptiPlex 990 with a nVidia GeForce 520 video card with 296.10 drivers including HD audio out
Windows 7 x64 with the OS configured to use the nVidia audio for output and to match my speaker setup
Audio/video is sent to a Sony STR-DN2010 receiver over a single HDMI cable
Receiver also configured to match the speaker setup I currently have
VLC 2.0.1

[nhelder]

Interestingly, if I enable "Bass Management" under Playback Devices > [My Device] > Enhancements (within Windows), I'm then able to get subwoofer output... though, I'm a little concerned that this might not be the best approach, so any feedback would still be appreciated.

[Jean-Baptiste Kempf]

Subwoofer could be activated only in 2.1 streams, maybe. No idea.