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I need some clarification on exactly what is meant by a statement from the PC manufacture of my computer. Right now I get sound via HDMI from my GTX 580 to my TV. I will be moving soon and am going to resetup my surround sound system to run off my computer. In that setup I can run the HDMI cable to the A/V receiver or I can run the individual cables from my card to the back of the receiver. If I can just use the HDMI cable and get the same sound quality as from the card I will be happy but I don't know if I can cause I am not sure what the following statement really means:

...utilizes a straight pass through cable connection from the video card to the HDMI signal.

To me this means the sound card is still doing all the processing and instead of directly outing from it's external sound out ports it is outputting to a cable that goes to the video cards allowing the sound to be passed along the HDMI cable and thus would give me the same quality sound from either direct output ports or HDMI. Is this correct thinking?

Edit:

On my system I have a "Creative Labs X-FI Professional Audio card (20K2) which is embedded into our custom motherboard." So from the sounds of things I am not using the 20K2 but a, probable, lower end sound processor on my GTX 580 and I would get better sound if I connected to the A/V receiver from the card directly. Also looking into what a SPDIF is it looks like I could use the Optical output from my card into the A/V receiver for full 5.1 sound from the card directly.?

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There is not much information about it so what I'm going to say may be not exact. As far as I know, graphic cards nowadays come with a dedicated Realtek HD Audio chip. Older graphic cards used a SPDIF cable coming from the motherboard's audio chip.

In the end it's pretty much the same, the rendering engine from the Realtek audio chips doesn't really change between different models, what changes is the input/output and functionalities. In a graphic card you except this chip to only provide a SPDIF output which will be connected to the HDMI chip (and then going through the HDMI cable), and being able to render PCM and AC3 with some proprietary Dolby technologies.

Even if the "core" is the same between your motherboard and graphic card audio chip, it's better to use the graphic card's one.

First, that makes only one cable, not two or even more.

Second, if you were going to use the Jack output and not the SPDIF output from your motherboard, you'll have an analog signal instead of a digital one. Given you would use some pretty long audio cable, if it is analog there is attenuation and degradation of the signal as well as interferences, degrading the quality (you may not hear the difference though).

Third, still about using analog output instead of digital ones, this means you would be using the motherboard's integrated DAC to output analog signal on the Jacks. I'm sure it is of a lower quality than a good A/V receiver, better use only the A/V receiver for this job. Also, most A/V receiver allows you to choose and tweak some Dolby Surround modes that are only available if they receive AC3 encoded digital signal. (either on SPDIF or HDMI)

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  • On my system I have a "Creative Labs X-FI Professional Audio card (20K2) which is embedded into our custom motherboard." So from the sounds of things I am not using the 20K2 but a, probable, lower end sound processor on my GTX 580 and I would get better sound if I connected to the A/V receiver from the card directly. Also looking into what a SPDIF is it looks like I could use the Optical output from my card into the A/V receiver for full 5.1 sound from the card directly.? Jul 28 '15 at 13:29
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    Ah yes I was assuming you had a common consummer motherboard with a Realtek ALC chip. I don't know about Creative hardware but it may be a better idea to use it then. (it if supports Dolby codecs) You should run directly an optical cable from your motherboard's TOSLINK to your A/V receiver.
    – piernov
    Jul 28 '15 at 14:07
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From what I have been able to tell, the HDMI sound from the PC to the video display device is being supplied as a seperate audio device IN the video card, or in the case of on-die grafics it is again a part of the cpu-gpu combination device. Your regular audio card, or onboard audio has nothing to do with it.

The information supplied by the hardware GPU manufactures leaves the audio side of the grafics cards out of the picture (pun), But there is no question on the software side as you can observe in the device manager , that there is lots of HD audio things ??? where the freak are they comming from :-)

In the menu of the device manager | View -> Show Device By Connection |, you can see where they come from. You could also disable them one by one, to see which one is outputting sound at the time (you might have to re-run a program that was using one, when you pull it out from under it).
In the control pannel, sound, playback tab you can select one or the other as the default.
In (only) some player/viewer/editor programs you can select the output device different from the default.

Because it is all digital and not an analog conversion, it is a much more raw kind of signal, and much simpler to exist out of each of the video devices HDMI digital uncompressed output. They are also simple, as less adjustment software has been supplied (so far) like the onboard or audio card will have.

The operating system and its filters and upscaled mixing and all still exists. Anything the OS was doing before the digital stream even reaches your other audio device, will still be in play. The OS things will all be in play prior to the digital signal leaving the OS software itself and headed to whatever audio device it is. To the OS it is (more or less) just another audio device.

Notes: When showing devices in the device manager an additional selecting of View Show Hidden Devices, may be useful to see items that are disabled, or not existing at that time.

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