Does the bit depth and sample rate of a sound card affect the 5.1 digital output?

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I need to transfer 5.1 digital sound from:

Laptop -> sound card -> home theater receiver (this does decoding)

I'm using the premium grade optical in/out cables to achieve this.

  1. Since my initial requirement is to pass 5.1 digital signals through USB to the home theater receiver, should I be concerned about the sound card's bit depth and sample rate?
  2. Can I use a cheap sound card which passes digital signals, or do I need a high quality, name-brand sound card?

inckka

Posted 2015-12-14T06:44:33.677

Reputation: 103

1S/PDIF was designed for stereo data, so 5.1 audio must be compressed (with a codec like Dolby or DTS). You are unlikely to get more than 16 bits at 48 kHz, which every hardware supports. – CL. – 2015-12-14T09:02:18.887

@CL. However since the decoding happens in the end device anyway and the bit depth and the sample rate being generated at the end device (home theater receiver in my case), I don't need to be panic about the sound card right? – inckka – 2015-12-14T17:10:42.937

The end device cannot create more bits or samples than are actually contained in the (compressed) data sent to it. And these algorithms aren't specified for more. – CL. – 2015-12-14T21:38:27.523

@CL. Can I know some models that works with linux. It should be output multichannel through spdif. I've already bought a USB device(famous ebay search, external soundcard) however it only supports stero on linux. – inckka – 2016-01-08T05:07:20.647

The Dolby/DTS compression must be done in software. – CL. – 2016-01-08T08:24:36.783

@CL. But my DAC does the decoding. So do you know any sound card – inckka – 2016-01-08T09:52:38.967

Compression is encoding. – CL. – 2016-01-08T10:23:27.313

Answers

2

Neither the quality of the soundcard nor of the optical cable is relevant here -- it needs to be good enough to transport data at all, but enything beyond that will not give you any improvement in quality. There is also no difference in sound quality between a coaxial and an optical S/PDIF output and cable.

As the data is transported digitally, and never decoded in the soundcard, any analog noise introduced in the sound card will be completely ignored by the receiver.

The only reason to go for "premium" products here would be if you need to bridge large distances, where better transmission quality would avoid errors, but that is completely irrelevant if it's just a few meters.

Simon Richter

Posted 2015-12-14T06:44:33.677

Reputation: 2 384

However there are markings on the optical cables like "Data Lose" and the high priced cables have a low "data lose" so it does affect the digital signal quality right? – inckka – 2015-12-14T17:11:56.730

1It affects the analog representation of the digital signal, so instead of a 1 you get a 0.97. As long as you don't get anything smaller than 0.5 when there should be a 1, the receiver can guess that this should have been a 1, and restores the data perfectly. – Simon Richter – 2015-12-14T19:00:58.150

This is really helpful information. There's another consideration. My laptop has a HDMI out, so what will be the smartest decision? is it buying an external sound card or a HDMI to /SPDIF converter? – inckka – 2015-12-15T16:40:13.903

1In many cards, audio over HDMI only works if the output is active. If you plan to connect a monitor there, the HDMI output would be the better choice, but if you just want sound output, the external sound card is likely the better choice. – Simon Richter – 2015-12-15T16:49:15.653

Thanks a lot for letting me know these. I've been researching good sounds cards online. And found external sound cards from USD8 to way above like USD100. Does this highest priced cards process 5.1 digital sound with more quality than the lower priced ones? – inckka – 2015-12-16T05:00:30.393

No, the data is not processed on the card, and the digital to analog conversion happens in your AV receiver, so there is no quality difference. – Simon Richter – 2015-12-16T05:16:37.243

if its OK, Can you do a product recommendation ? – inckka – 2015-12-16T06:07:02.377

Not really -- any recommendation would be based on driver quality, not hardware, and as I don't use Windows, I cannot comment on that. – Simon Richter – 2015-12-16T06:20:41.860

Let us continue this discussion in chat.

– inckka – 2015-12-16T06:27:13.467

I've bought a cheap sound card from eBay with a SPDIF out. It isn't being recognized as an SPDIF device on Ubuntu. it shows as an stereo device. No Help Do you have any other sound card recommendations? – inckka – 2016-01-21T04:49:01.400

Asked: 2015-12-14T06:44:33.677

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Active: 2015-12-16T01:41:53.953