If you don't think your Real Tracks and MIDI parts sound like they occupy the same "sonic space", it may help to get a small mixer with effects (like one of the Behringer series)
Route the MIDI and Audio into different mixer inputs, and add a light sheen of reverb to unify the whole mix. When played together, this seems to make all parts sound like they're in the same room.
You could accomplish the same thing if you are running both parts into a PA mixer that can add light reverb reverb.
When recording, you can add the reverb to the entire mix at the end