I completely understand the frustration with finding a stable driver for an older hardware component like the C-Media PCI audio card on Windows 10. Unfortunately, as technology progresses, support for older hardware can sometimes lag behind or be dropped altogether.
One approach you might consider is visiting third-party websites that host a collection of drivers. Websites like DriverGuide or even archived versions of older software on sites like OldVersion.com might own what you need. However, always ensure that you scan downloaded files for viruses and malware with a reliable antivirus program before installation to keep your system safe.
Another potential solution could be running the audio card in compatibility mode. You can set the driver installation program to run in compatibility mode for an earlier version of Windows where it was known to work. Right-click on the installer, go to Properties, then Compatibility tab, and select an earlier Windows version.
If all else fails and your work or audio needs rely heavily on having stable sound processing, it might be time to consider upgrading to a newer sound card that explicitly supports Windows 10. Modern cards aren't too expensive and offer better performance and support.
Remember, tinkering with drivers can sometimes lead to system instability, so always make sure to create a system restore point before proceeding with installations or updates.