Selected audio device changed from Razer Surround to Realtek Audio

Hello, I'm using the Razer Surround 7.1 app and have it selected as my default output device. However, after a few restarts the Realtek Audio device gets automatically selected as default audio device, effectively disabling Razer Surround. This is very annoying because not only do I have to manually switch back to Surround, but I also have to reconfigure all apps using audio input. How can I fix this? I cannot uninstall the Realtek driver because if I disable it I have no sound at all (Razer Surround uses Realtek in my case). Regards