I have the same problem.
I havent used PowerDirector for a while (two months) beacuse my mic broke on me, so I got a new head-set yesterday (Razer Kraken) and when I went to record with PD15 It had to be updated so I did. I then tried to record my gameplay but everytime I did a screen capture (that´s how I record my gameplays) the result was a very bad distorted sound output (game output) and very high. The mic recorded was ok but the game output was horrible.
I tried all the settings I could on PD15 and on Windows10 but nothing got rid off that nasty overloaded distortion!
I then tried recording the same gameplay with nVidia ShadowPlay (nVidia Experiance) and everthing worked fine, no issues with game output. So my guess is that it has to do with the recent PD15 update, as before this update everything worked fine and I didnt have to do any ajustments to PD15.
I hope we can get a fix on this.
Best regards.
Red