# Getting 5.1 over toslink/optical with Z5500



## Praetor

Hey all, probably a simple tweak somewhere that I'm missing.

The facts:

 All of the audio I am playing is actually 5.1 (AC3 448-640, 5.1)
 The speakers are the logitech z5500s connected over analog (3x stereo jacks) as well as the toslink/optical connection
 The sound card is an onboard  ADU 1988B (8channel onboard with coax/optical connectivity)
 AC3 filter (rev1.46) is installed and the output format is "SPDIF Passthrough for AC3", "3/2+SW 5.1 channels"
 FFDSHOW  (rev1700) audio configuration is set for 16bit output wit the "AC3 (SPDIF encode mode)" and "Encode only 5.1ch streams" boxes checked.


The problem:

 When playing 5.1 content over the 3x stereo connection, my speaker's display reports "Input: Direct 96 24, Effect: 6 ch Direct". This is good and it plays all the channels correctly.
 When playing 5.1 content over the optical link, my speaker's display reports "Input optical, Effect: _____" where "____" is "Stereo, Stereo x2,  DD PLII Movie, DD PLII Music" (DD PLII = Dolby Digital ProLogic II). This is not good as it essentially means that the speakers are receieving stereo data and using the (retarded) pseudo-5.1 "enhancement" to output stuff on the rear speakers. If I was listening to stereo music that would be great but my entire audio collection is 5.1 so that's actually detrimenal.


Anyone know how to work around this? Maybe I'm missing something like the decoder on the Z5500s cant handle AC3 or they cant handle it over optical? (which would seem dumb). I'm guessing its an AC3 setting I've fuddled up.



From the speaker's information page we get the following:



			
				Logitech said:
			
		

> Hardware decoding:
> Dolby® Digital, DTS®, and DTS®, 96/24 soundtracks
> Dolby Pro Logic II (Movie and Music modes)
> 6 Channel Direct
> Stereo x2
> Stereo
> 
> Supported digital formats:
> Dolby Digital
> DTS and DTS 96/24
> PCM (uncompressed stereo): 44.1 kHz / 16 bit through 96 kHz / 24 bit
> 
> Source Inputs:
> Digital optical for DVD or CD players, PlayStation®2, Xbox®**
> Digital coaxial for DVD or CD players or PC sound cards (requires coaxial cable, sold separately)
> 6 channel direct (3 stereo-mini connectors) for 2, 4, or 6 channel PC sound cards OR
> 6 channel direct (3 stereo-mini connectors) for 3 stereo analog mini audio sources, like CD and DVD players, Playstation 2, Xbox, or 2 channel PC sound cards (somedevices may require stereo mini to dual RCA adapter, sold separately)
> Analog stereo-mini (on side panel of control center) for portable CD, MP3,or MiniDisc® players




Now unless I've mistaken something, "Dolby Digital" and "AC3" are, for all purposes here, the same thing and so, "it should just work". Thoughts?


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## Praetor

Problem solved.
Did that in Media Player classic, now seems to work for all players.


Note that with the passthrough any "system volume control" no longer works (i.e. any software volume control be it my keyboard, windows sound control etc). As all the decoding is offloaded to the breakout box, that box is responsible for handling volume as well.


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