I have Sound Balster Z and SteelSeries Siberia 800 headphones. Both support Dolby Digital Live encoding. I have connected the Siberia's base station using optical cable to the Sound Blaster's S/PDIF output.

I have the option to turn on DDL in the Creative control panel. Sound Blaster Z Control Panel

I also have the option to turn on "Dolby" in the Siberia base station options.

Alternating between the two options produces (subjectively) different sounds. Turning both on at the same time introduces crackling in the background.

I was wondering if anyone could explain whats going on and what are the proper settings for DDL and headphones connected through S/PDIF?


First off: I was not able to find proper specs or even a manual. So most of this is based on what’s “normal”.

The headset does not feature Dolby Digital Live (AKA encoding). It can decode Dolby Digital, because otherwise it could not receive 5.1/7.1 over regular optical/coax digital connections. (Only newer connections like HDMI have enough bandwidth for uncompressed multichannel audio.)

It most likely also has a Dolby Pro Logic decoder. This is what you toggled.

As such, you must activate Dolby Digital Live on your sound card. Otherwise, it will continue to output stereo over its digital outputs.

  • Seems you are right. But why would toggling Dolby Digital Live encoding and Dolby Pro Logic decoder at the same time produce crackling? Shouldn't they work together? – mrmartan Sep 1 '16 at 7:38
  • Dunno. Using a Pro Logic decoder on sound that already is 5.1 is pointless, though, so I wouldn’t worry too much. – Daniel B Sep 1 '16 at 7:40

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