Do I need special headphones or in-ears to experience 3D sound?

No. KLANG incorporates binaural technology and processes the sound inside a KLANG processor to work with your own pair of standard stereo headphones or in-ears. In fact, it is not important if your headphones are open or closed, electrostatic, dynamic or use balanced armature drivers as most in-ears do. You can use universal fit in-ears or custom molded in-ears. Just make sure that the polarity is correct and the left and right signals go to the correct ears.