Well actually I kinda found something myself. I don't know why I didn't try it the moment I saw it, which was more than a while, but still.
When you start a game you can click on the bottom right on your dekstop screen on the speakers icon, from there choose mixer and you will find (or at least I do) Nvidia Caputre Service (or something like that). When you mute that thing from the mixer the sound you record from your VoIP client sounds normal. That is tested by me today and it worked.With it being on the other sides voice was echoy and overall broken, but when I turned it off it sounded completely normal, exactly as I heard it when I recorded it.
Give it a try and tell me if that worked for you.
If it did hopefully there is a way to permanently shut that thing off, otherwise you would have to mute it everytime you start a game.
