As I think you've recognized in your other thread, it might be appropriate to do a Windows reinstall rather than trying to fight the symptom with a new sound card (e.g. your USB idea).
If you have the ability to do a "system image" backup (so that you can easily restore your current environment after the experiment, if it proves unsuccessful), I'd do that and then do a fresh from-scratch Windows reinstall. Likelihood is very very high that your sound using onboard ALC892 will once again work perfectly. Don't forget to also take a "data" backup/copy of your data on C, in case you go forward with the full reinstall from scratch and need to get your data back as well as just reinstalling your software program products.
If so, then you can proceed with the rest of the full reinstall (we all do this every so often, even if it's only every few years, when corruption or other insurmountable unrepairable problems have no other solution). If not, then you can restore the current "system image" and try another hardware sound device as a solution (although I honestly wouldn't want to continue operating with known fundamental corruption in the Windows audio system, even with a new second sound card that might work).
I have a very similar P8Z77-V Pro board with the same ALC892 chip on it, and there's no problem with audio. In my opinion some unrepairable corruption in Windows has caused your current symptom, and it sounds like this is just one of those triggers for the "every so often" Windows reinstall. It's just not worth any additional energy to try and "Registry clean" the corruption away. You'll be much happier spending the 2-4 days it'll probably take you to get your complete system reinstalled and fully operational again, and working perfectly.
