your HRTF is personal
What is the problem?
If your ordinary headphones can produce 3D audio, then why is 3D audio not as common as 3D vision? Because it needs extensive personalization to work well. For 3D vision this is not necessary: the distance between both eyes is similar for everyone, so the same pair of goggles, with small interpupillary adjustments, will work for everyone. However, for 3D audio such a one-size-fits-all solution does not work. Everyone’s head and ear shapes are really different, so their interactions with sounds are really different as well (i.e. HRTFs are really personal). Consequently, everyone hears the world differently and this spoils the 3D audio experience dramatically: sounds that should arrive from the front appear from the back, etc. Often, the 3D effect disappears altogether and all sounds seem to come from inside instead of outside the listener's head. Therefore, to experience real 3D audio it is necessary to account for your unique head and ear shape by means of a personal HRTF.