Audio streaming - how to mute speakers

[belltown]

I'm streaming my Stereo Mix output from my laptop running Windows 7 to my TV's speakers from my laptop running WIndows 7 using VLC media player streaming to a Roku box. Because of the 30 second time delay, I'd like to mute my laptop's speakers and only have the audio come out of my TV speakers. However,if I try to mute the speakers, it mutes my stereo mix output as well and I get nothing from my TV. Does anyone know how I can mute my speakers and still stream the audio from stereo mix?

[VLC_help]

Physical mute via mixer?