PC audio cards to Processor

Hello, my question is probably out of the scope of this forum but I will ask any way.
I have decent audio system Mcintosh amps, processor Magico speakers etc.  The system is used for three purposes, home theater movies, stereo music and surround sound PC video games.  I connect the PC audio card to the processor via optical out from the audio card.  In order to get 5.1 surrond I have to set the audio card to 2 channel output even though it is a 5.1/7.1 Dolby DTS card.  If the audio cards software is  set to 5.1 etc. the result is stereo where only two channels received by the processor and converted to stereo on the system.  My question is this, does the processor convert the non Dolby non DTS two channel signal into dolby 5.1 surround.  In other words if I am using a quality PC audio card that is not Dolby and or DTS cabable and is two channel only (made for headphones) does the Dolby DTS enabled processor in this case a Mcintosh convert that two channel signal into the 5.1 surround signal?  

One other question:
Can anyone recommend the best internal PC audio card for 5.1  home theater use?  When PC audio cards are reviewed its almost always for use with headphones and not for componet (processor multiple amps mulitiple subs) driven home theater systems.

Thank you.
there are no internal audio cards currently that use hdmi.   Please correct me if I am wrong.  I could possibly go out through GPU Nvidea HDMI however   the onboard, motherboard GPU audio is crap. I thank you for the input however my question is not addressed.  Perhaps I did a lousy job of putting into words.
HDMI provides full 5.1 digital output.

You don't even need a sound card for it. :)

You just have to select HDMI as the default audio. :)
Eric you lost me.  If you are not using an audio card, motherboard onboard sound then what is sending the signal to the processor?  I have a Falcon northwest computer with Nvidia 1080ti in SLI.  Currently The PC sound card, an Asus, is connected to the Mcintosh 122 processor.  If I was to remove the Asus card what HDMI port would I use to connect to the processor?
Sound cards are only needed to do the digital to analog conversion on the PC. However, that's not the only place this conversion can occur.

If you are using HDMI, there's no conversion. It sends the digital data stream including audio and video to your TV or processor, and the digital to analog conversion happens there.

You would connect your Nvidia directly to your Mcintosh processor. I notice you only have 1 HDMI port there. If your motherboard supports HDMI output you may be able to use it too if you need 1 for your monitor and 1 for your TV.

The gpu 1080Ti is in SLI I have two graphics cards with an HDMI out on each card.  one is already dedicated to the TV.     So the video game sound signal goes to the graphics card in addition to the video signal or are the combined? Would you explain in detail how to adjust setting in control panel to send audio out the unoccupied HDMI in detail?
Assuming Windows 10:

In the search bar:
Search for : Control Panel
Click on: "Hardware and Sound"
Underneath Sound on the right click on: Manage Audio Devices.

You may even be able to change your digital output there. :)


If you want to try to usue 5.1 from a digital output, once you are there, select "Playback" tab, and then select your digital output, then "Properties" and finally, "Supported Formats"
I also want to point out, you may wish to go this way:

Nvidia --> McIntosh --> TV

as this will let the Mc decode your audio directly. The other way:

Nvidia --> TV --> (via ARC) --> McIntosh

may work, but you have to use the right ARC port, and it’s iffy. If you already have it working though, you should be all set.
If the audio cards software is set to 5.1 etc. the result is stereo where only two channels received by the processor and converted to stereo on the system.

I have experienced this same thing when viewing sources that send Dolby Digital Plus, such as streaming sources like Netflix. On some streaming devices, it doesn’t properly convert this to "normal old Dolby Digital" over s/pdif (i.e. toslink). The result is only 2 channels of the 5.1 being decoded and played by the processor. In my system, I HAVE to play Netflix over HDMI because that’s the only way the processor will properly receive and decode the Dolby Digital Plus signal. That being said, old school Dolby Digital and DTS is always compromised when sent over HDMI. You end up losing dynamic range and naturalness of the sound. The only thing HDMI is good for is the high resolution bluray audio formats (DTS-MA and Dolby TrueHD).

This could be a characteristic with your software or your device driver level or something else entirely. I don’t know what configurability you have currently, but see if there is a way you can configure your system to output 5.1 PCM over the spdif output instead of compressed DD/DTS. This is more supportable to processors sometimes.

As far as S/PDIF cards, the best one that is readily available now is the Asus Xonar Essence. It came in a few models (ST, STX and STX II). They all have an excellent RCA digital COAX output that also supports Dolby Digital and DTS. Drivers are available for download in Asus website and all support up to Windows 10 64-bit. The card is kind of overkill just for an spdif output because it’s costly and it’s also a full analog audio sound card, but there really isn’t anything else better. You can always find a used STX model on ebay for $50-100. If you can find a Musiland Digital Times PCI card, that’s a better spdif output, but they do not appear to be available anymore.

I cannot tell if the Xonar Essence will solve your dolby digital problem because I do not have direct experience. I can only advise on the best spdif computer card.
That is the card that is currently installed, Asus Xoner Essence STXII. The reason I am asking about this stuff because I will have a new gaming machine built, when Nvidia starts using HDMI 2.1.  The PC builder uses Sound Blaster cards, I don't like them.  I have been setting the Asus card to dolby digital live on two channel with the A/V processor set to game dolby etc and it works, all amps subwoofers are needling. I tried what you suggested by going  into the Asus control panel and switched it from Dolby live to PCM and changed from two channel  to six channel and maxed out the sampling rate.  The result was noticeable it really woke up the speakers.  I switched in to 6 channel from two channel thinking that was appropriate because I have two fronts , center, two surround and two subs.   Thanks, your advice  improved the sound.
Great!  However, I would recommend setting your sampling rate to 48khz because SPDIF really cannot transfer 6 PCM channels at 96 or 192 khz.  Also, Dolby Digital / DTS would be a compressed version of 48khz anyways.  This way, you can ensure that you're getting the maximum capable bandwidth of spdif and keep full support of your McIntosh processor.

If, at any time, you want to listen to some 2-channel hi res 24/96 or 24/192 songs, you can always manually go into Asus control panel and switch it back to 2-channel PCM at 192.  But for gaming and movies, 48khz will be excellent anyways.

For the future gaming machine, unless the system or games will generate the hi-res bluray audio formats (DTS-MA and Dolby TrueHD), you are still better off keeping the Asus Xonar for digital COAX s/pdif audio output.  Hmmm, maybe setup two input configurations on your McIntosh.  On input that uses HDMI + digital COAX for audio, and a second input configuration that uses HDMI for both audio/video.
I noticed that the sampling rate received by the Mcintosh is displayed  for a few seconds when the game boots up and audio signal is incoming to the processor.  When I maxed out the sampling rate in the audio card control panel to 192 khz it is displayed by the Mcintosh as the signal being received for processing.  Is this display of sampling rate on the Mcintosh of 192 kHz an exception  to what you said earlier that optical cannot transfer 192 kHz?  Please advise.
s/pdif can transfer 192 khz, but only for 2 channels.  When you try to push 6 channels, I don't believe it will support it.  If it seems to work with 6 channels at 192khz, then maybe something is different.

Also, you said you have the Xonar Essence STX II.  I don't believe this card has an optical output.  Only a RCA digital coax output.