The reason is the audio would for reasons I won't get into here be out of sync and would result in owners demanding a fix. So makers rarely have this feature.
Samsung has NO SPECS at http://www.samsung.com/us/support/owners/product/2008lcd-tv-a330 so I can't supply a fix for this one.
How do you set analog speaker output be turned on. The sound / tv speaker / on/off seems to have no effect on headphones

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