I owned an A3D 1.0 sound card from back in '99. The card cost $15, nothing special. It used psycho-acoustical algorithms to mimic sound coming from different directions. It did it so well, I could kill people in Counter-Strike entirely based on their foot steps. I got lots of kills through walls.
Eventually I convinced my cousin that A3D was much much better than Creative's EAX even though several times cheaper. He finally switched over and got an A3D 2.0 sound card for $35. Shortly after getting his sound card, he installed new video drivers and mid game in CS, all the player models stopped displaying. He was unable to see the enemies, so he hid. After a bit, his team was dead and he was the only one left. He killed 4 people on his own without being able to see them. Even beat one in a knife fight. That is how good the 3D sound was.. BACK IN 1999!!!.. WTF
Headphones were actually better because it so perfectly mimicked directional sound that having a fixed distance between your head and the speakers meant perfect hearing.