The best place got ask this question is at Focusrite's web page. They do Focusrite 24/7, all year long. I'm not even sure about what you are trying to do based on this thread. MIDI itself has no mono or stereo. It is just a series of on or off messages. Your sound source has mono and stereo. If your sound source is indeed your computer/software, you would have to monitor it somewhere, but your Focusrite has a knob on it that mixes the original and the recorded signals. You can turn it one way or the other.

Focusrite can probably answer your question in less than 10 minutes.