Question

I have a MIDI cable in my keyboard out port running into my Audiobox96 in. Do I have to add another MIDI cable from the Audiobox 96 out to the Yamaha MIDI in?

Answer 1

No, not really. For recording parts you play  you only need the one cable you've got. You could use a second cable if you wanted to control certain functions of your keyboard from Studio One, e.g. program changes on the fly.  But with a DAW, this is an unlikely scenario. Hope this helps.