Satellite pro speakers don't mute with external speakers

[ChrisRX]

I have a satellite pro a120-146 which uses the intel audio chip. The speakers in the laptop aren't very good so I use external speakers plugged into the headphone port. I can select the headphone switch and the sound will then come out of the external speakers as well as the internal speakers.
I have 2 volume channels, PCM and Front, Front will control the volume of the external speakers and keep the internal speakers the same volume and pcm will change the volume of both sets of speakers.
Is there any way to mute the internal speakers only?

[johnvixen]

I have a similar problem, if anyone has any advice please let me know.

thanks
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