Depends on the make and model of your TV.
Many TVs won't let you use the internal TV speakers at the same time as the audio output.
If the TV has a headphone jack the TV speakers usually go off when you plug in headphones so you would need to split the headphone output and connect both your headphones and self powered speakers with their own volume control to the TV. A tech could modify the headphone jack so the TV speakers don't go off when you plug in headphones but the volume of the speakers and the headphones won't be separately adjustable..