Hi,
It depends on many factors such as audio card, application configuration. As far as I know, only one playback device can be set as default. However, some media players and games will let you choose which audio output device to use instead of the default
one.
You can refer to this article.
http://www.tomshardware.com/forum/302112-31-dual-monitors-split-sound
Niki Han
TechNet Community Support
