So from the manual:
The original Quadraphonic format for music, with one speaker in each corner. This format was intended for vinyl record players.
I was expecting a bit more detail, unless I’m missing it…
Why would I use this over stereo?
Thank you
You would never use this. LOL. This was the 70s’ attempt at surround sound. Never caught on. Some important releases from the time were in Quad, so, since it doesn’t cost Steinberg anything, they’ve maybe included it so that Quad tracks could be imported and remixed/remastered.
I see, thanks. I’ve seen it in a few tutorials, such as: http://www.native-instruments.com/en/support/knowledge-base/show/903/how-to-create-a-sidechain-effect-in-cubase/ > so, just wanted to make sure I wasn’t missing out on something cool 
To be honest I have not seen many people mixing in surround sound 5.1.
I suppose I am not surprised given the decline in HiFi and the upsurge in ipod/Phones.
Yeah, there was that moment, when 5-1 was coming out, that we all thought it was going to be The Next Bug Thing[emoji769]. You couldn’t pick up a Mix magazine without reading about how some band was remixing their classic album in 5.1.
But, like Quad, DVD Audio, SACD… It failed. People have proved, over and over, that hi-fi is about as far as they’re willing to go—if they have to pay a significant amount to get the rig.
As CD Audio dies, and we move to digital-only, we can now use high-res files. There are several players that will play higher-res files. But, again, do the masses care?
If you found yourself mixing music for surround.
In a 5.1 surround mix, the LFE is typically only used for sub-sonic frequencies while the center channel is primarily reserved for dialogue. Therefore, many engineers mixing music for surround (for whatever purpose) might opt for using only 4.0 channels, and “quad” is simply a descriptive term to represent the 4.0 channel arrangement.
If a manufacturer made headphones for 4 ears and humans somehow evolved with 4 ears I think it would be pretty swell.
Music for aliens?
Audi Quadro ?
Oops sorry
Audio Quadro