Hi,
Is HDMI selected as the default audio playback device in Control Panel, Sound?
I have no idea who the manufacturer of your PC is and what your model number is.
I have an HP PC, circa 2013, with Beats (IDT) audio that was originally shipped by HP with Win 8.1 installed as the factory operating system. Upgraded to Win 10 and had audio problems with the Win 10 audio driver provided by Microsoft. There were no errors but audio was not running correctly.
Removed Microsoft's version of IDT software and installed the HP version for Win 8.1 on the new Win 10 installation and it fixed the problem.
I realize you have Realtek audio. If Realtek is not providing a Win 10 audio driver for your audio chipset then the Win 8.1 version provided by the OEM may work if you were running Win 8.1 prior to the upgrade to Win 10. Otherwise, have you checked
Realtek for updated Win 10 audio drivers for your specific Realtek audio chipset?
Jaco