Most amps that offer balanced inputs also offer unbalanced inputs, and while they typically include some way to manually identify which input to use (such as the toggle switches for each channel of the 7700) Outlaw still recommends not running both unbalanced and balanced interconnects between a single channel of the processor and the amplifier. In your system, for example, running the unbalanced front outputs to the SA amp and the balanced front outputs to the 7700 is different than running both balanced and unbalanced to the 7700. The first approach is fine, while the second isn't so desirable.

That's going to be one heck of an "office" system, by the way. It should be a lot of fun once all the pieces arrive and get hooked up.