You need to select external speakers in your tv menu system. Otherwise, the tv will keep playing sound throught the tv speakers. I do the same with samsung smart tv's and cheap 2.1 logitech speakers, using the 3.5mm jack.
With samsung I still have to turn down entirely the volume of my tv, becouse even with the option of external speakers, the tv play sound in both outs at the same time.
How do I disable my Samsung 2014 TV's internal speakers?
Last Update date : 2016.04.21
Note: not all Samsung TVs have the Speaker Select function. To verify if your TV has this function please check your user manual. (A free downloadable copy of the user manual is probably on the product web page for your TV).
The Speaker Select function differs from the Mute function. The Speaker Select function turns off the TV's built in speakers but it does not disable the audio out ports. Home theater systems, speakers and/or or receivers attached to the audio out ports will continue to output sound. The Mute function turns off all audio, including that produced through the audio out ports.
Follow these steps to use the Speaker Select function to disable your TV's internal speakers.
1. Press the MENU button on your remote control.
2. Navigate to and select Sound.
3. Navigate to and select Speaker Settings.
4. TV Sound Output will be highlighted by default. Select TV Sound Output and open the pop-up menu.
5. Navigate to and select Audio Out.
6. Select OK at the bottom of the page to save and exit.
When you turn on the Audio Out (Internal Mute) function the Mute button on your remote control will not work.
The instructions above work for most Samsung TVs that have the Audio Out (Internal Mute) function. They may not work for your TV. For exact instructions see your TV's user's manual. You can find free downloadable user manuals on most product pages on the Samsung website.