Welcome Quadlearner!
The "Ask SW" section is definitely not the right place for your inquiry, but I'll do my best help you out. The mods will probably move this thread eventually.
This is a particularly complex and popular subject here- there are in fact entire sections of the forum devoted to it.
https://www.quadraphonicquad.com/fo...-Sound-Production-and-Playback-on-the-Desktop
https://www.quadraphonicquad.com/forums/forumdisplay.php?91-Multichannel-Media-Players
Not exactly sure what you mean by this- you are trying to transmit the output of a quad decoder through your computer and into your stereo? what would the point of that be...just plug the outputs of your quad decoder into your stereo.
Also can you be more specific as to what "quadraphonic" source you are trying to playback- an old SQ decoder, CD-4 demodulator, Q8 or reel tape deck, etc?
I assume what you actually mean is you want to playback surround music files from your computer- that is absolutely possible.
What many of us do here is we rip our surround discs, records and tapes and store them as multichannel music files on our computers, which we can then playback into our stereos. There are several file formats that support surround- FLAC, ALAC, WAV, and you can also playback directly demuxed audio codecs (.AC3, .DTS, .MLP, etc).
This sounds promising- I assume it take USB from the computer and puts out the 4 channels? If you provide the model number I can tell you if it will work.
Here is the one I use-
https://www.amazon.com/Creative-Blaster-Surround-System-SB1095/dp/B0044DEDCA
A number of computer programs will playback multichannel music files- Foobar2000, VLC Media Player, and Creative PowerDVD to name a few.
I personally use Foobar2000 as it is free and easy to mod. Additional features needed for surround are the DVD-Audio, DTS, and SACD decoders, which are on the Foobar website.
http://www.foobar2000.org
Here is what my Foobar looks like...if you look around you'll see other members' Foobars here have fancier front-ends, but for me this does the job.
Keep in mind that when you first download, it is essentially a blank canvas- all of the meters, decoders, and other visualizations are optional components you can add on later.
View attachment 31895
If you need help setting any of this up or learning how to rip your surround media, just drop me a PM or post. You'll find most members here are friendly, reasonable, and very well-versed in the surround computer stuff.
This hobby can be a bit of a hassle for the uninitiated, but once you get going you'll never want to go back. Luckily you've come to the right place!