Well he could buy a usb sound blaster 2 go card, hookup his headphones to it.
His sound blaster usb headphones would be default audio device, his mobo sound card would be communication device.
I fixed my problem with that 2 years it don't have any more problems from it.
https://www.amazon.com/dp/B0044DEDC0/?tag=httpwwwtechsp-20
When he is in game he will need to point the audio settings to point at sound blaster or whatever secondary sound card.
Now if he doesn't want the headphones, all he has to do is disable default device from it.
Also if he wants music or what not windows media player or whatever player will catch the audio.
Unless something else pops up and interferes and wants dibs to the sound card making it more aggrevating.