Really guys???
I find this useless. Just learn the sound of your headphones and mix compared to music you know. Also, there's just no way you're going to get a true 5.1 surround sound representation with normal monitor headphones.
If this thing is altering the sound via some sort of EQ, how does it know the frequency response of the headphones the person mixing is using in order to compensate for it? And obviously it's gotta be running through some kind of reverb which would be totally unproductive. Eliminating the room sound as much as possible while mixing and mastering is the goal so we can hear what we are mixing as true as possible, isn't it?
I feel like I've gotta try this just to laugh at it. Am I missing something?