There is no dedicated headphone socket on the DIR-165BK.

As you can see from the picture below, there's a LINE OUT jack, which is not a HEADPHONE/AUX OUT jack.

So that means you can connect headphones, but the sound of the radio will not be silenced.

But it is important to know that if you turn down the sound of the radio, the headphones must have their own volume control to be able to hear sound on the headphones.