Since you say the problem resolved itself when you reinstalled the Nvidia sound driver, it would be a problem with that device. I would suggest you seek help on the Nvidia forums.
If you have had the same issue on two different computers...
Could to be your network? How is the IP traffic when this is happening?
Are you using current antivirus and anti-malware software? (viruses infect the computer) (Malware infects the web browser)
Ok, so the roots of the problem are, at least to some extent, discovered. I searched the Internet all over and finally stumbled upon DPC latency issues.
I used DPC Latency Checker to verify whether my PC is having some latency problems and it reassured me that I had.
Then I used Latency Mon for further investigation. I found out that there's one driver having extreme latency issues (with the highest execution time over 86 ms): ndis.sys. It's a WLAN related thing and I could confirm that by switching off my WLAN adapter. Without the adapter working, no latency issues or stuttering ocurred.
Moreover, I can now tell that Internet speed is another problem. It seems that if I put my router far enough from the adapter (that is around a meter away), ndis.sys latency drops to an acceptable level, but the Internet connection is usually worse too. Even if not, why do I have to put the router further to make the audio run properly?
I reinstalled drivers of the WLAN adapter several times with no effect. I tried older ones from the CD included in the adapter box, as well as the newest drivers from ASUS website. It's a PCI-E N-10 model.
If anyone would like to help or knows something about this kind of issues appearing on Win 10, I'll be glad to hear your pieces of advice.
You might want to contact Asus tech support for help. There might be a firmware update to address the issue.