That sounds annoying. I think you have a bunk system. I have never had this happen on either my launch PS4 or the Pro, and I have used them both quite a bit more than you have.
Oh I know it's not an intentional issue or something too common on PS4 Pros.
I've always hoped it was more so a simple software issue with the PS4 Pro rather than a hardware issue, since the system runs fine otherwise (the only time the OS is slow is in the store or when I'm playing a very demanding game and using the main PS4 menu).
That being said I guess I should really stop being lazy and look for a fix. It's possible it's just something I need to tinker around with. Usually I just restart my console. It can be annoying though especially when you start a high-octane action game and realize minutes in that your sound is screwing you up