Topic: Digi96/8 Pad + Quicktime

I have a problem with Quicktime on my system: Quicktime works fine with the Realtec HD on board sound card, but not with the Digi PAD. I deactivated the onboard sound, cause if I watch a video, I want to hear the sound from my Digi and Programs like PowerDVD switch always to the onboard sound, if activated. But then if I start a mov-file, Quitime stutters. Its the same in Cubase: I cant use the Quicktime plugin. For testing I installed an Edirol UA25 and Quicktime worked fine. But that?s not a solution, if you have an RME!
I often get mov files from clients and it?s a bad thing to to convert them into avi for eg. to work with them.

Does anyone know this problem, or has a solution?

Windows 10 Pro 64bit Core i5, 16GB Ram, FirefaceUCX Cubase 10, WaveLab 9.5