ATC sound causes stutter in image

Hi all, I hope you are doing fine

I would like some assistence with the following problem I have:

When using FS9, (and FSX) on Windows 10 Pro - 64 bit, and with a USB external sound card, I get an annoying graphical stutter, for a microsecond or so, 

when talking to the ATC, or when another AI pilot is talking to the ATC..

I remember I had this problem years ago, on Windows 7, and for this reason I bought the sound card, which fixed this problem

But now, on W10, it is there again..

Could someone please help me fix this stupid problem? I have googled this but I did not come up with a fix

Thanks!