Connecting 5.1 Z906 Speakers - Is SPDIF Optical better ?

[marcusob72]

Hi, 

I have the ROG x670E Crosshair Hero MB, and am getting some x906 5.1 speakers. Is it better to connect them together with the SPDIF optical output from the motherboard to the Audio system, will I still get 5.1 audio from games ? I've read mixed messages, with some people only receiving stereo through the optical. I just want to play games with surround sound, probably wontn be watching movies at all.

[Shenny]

I am also owner of Z906 but my motherboard is previous generation (X570 chipset), if this matters at all. I prefer SPDIF because of the hardware decoding of DTS and Dolby Digital streams when I watch movies. For games this is not so important but, in my opinion: 1) I get deeper and more smooth bass compared to the "regular" speakers output; 2) SPDIF standard is stereo, AFAIK, but I use the virtualization function from the Z906 console to convert it to 5.1 output in games and I can't tell the difference.

Take note, however, that I have paired my audio system with premium Creative AE-7 Sound Blaster card. With the Realtek sound that comes with the mobo the results might be different but the Audio codec for Crosshair mobos is considered to be of high quality.

[marcusob72]

Thanks for the advice. When you say you prefer hardware, do you mean the motherboard hardware for decoding, or the Z906 hardware for decoding ?

Also the optical cable so does that means if you use it, you only get stereo output from the MB, but then the Z906 will convert that to 5.1 anyway ?

I presume if you use the RCA cables then thats the only way to guarantee the MB is doing the 5.1 decoding, so which sounds better ? Is the MBoard decoded sound or the Z906 deoded sound ? 

[Shenny]

After a short research, I must backtrack on some of my statements about the SPDIF standard. 🙂

By hardware I mean the Z906 hardware for decoding. When DD (AC3) or DTS stream is passed through the SPDIF audio output to Z906, it will decode it natively (the "Decode" light indicator on the Z906 console is on). Note that the "Decode" indicator is off if the same audio comes from the non-SPDIF output of your mobo/sound card.

However, contrary to my belief, SPDIF spec does support 5.1 surround sound but with the following limitation: "S/PDIF can carry two channels of uncompressed PCM audio or compressed 5.1 surround sound (such as DTS audio codec or Dolby Digital codec); it cannot support lossless surround formats that require greater bandwidth."

Some sources here:

https://en.wikipedia.org/wiki/S/PDIF

https://forums.tomsguide.com/threads/spdif-optical-support-5-1.355076/

Even compressed, I find the sound passed through SPDIF for much better in quality on Z906. You may notice the difference yourself when testing with a movie with DD/PCM/DTS audio stream (or with any other source with such audio streams).