If you go back and look closely, I’m willing to bet that the headset says it supports VIRTUAL 7.1 surround sound. It’s not true 7.1, but digital signal processing allows the headphones to fool your brain into perceiving multiple sound sources. If you think about it, you only have two sound inputs, right - your left and right ears? By slightly delaying or changing the volume of sounds, virtual surround sound can be quite convincing and really feel like you are in a three dimensional audio environment. There are a few headphones with multiple drivers per side, but you don’t see these very often, so I’m still betting that the ones you were looking at were virtual surround.