Hey guys, wanted to let you know that it also worked for me.
I have an Astro A50 and I am using the Realtek SPDIF Optical Audio Output. I was just able to fix it by disabling all effects / equalizers. But then the sound was very flat and not good. I installed the APO Equalizer and now I can re-activate all effects and my ASUS equalizer. Sounds pretty nice now. Thank you!