Does Cubase 7 allow you to have more than just 4 studio outputs on the control room? I find 4 separate mixes very limiting as I more often than not work with 5 musicians at a time, who all want to have their own individual headphone mixes.
I believe the Control Room is limited to 4 Que sends. However there is a “dirty” workaround for getting a 5th Que mix. Set up a mix as a regular send and route it to one of your audio interface’s outputs. This is how it was done before Steinberg introduced the Control Room feature.
Of cause, this won’t give you access to the Control Room sections Que mix features for this fifths Que. It is one option to try, in a pinch, though.