Recording / "Bouncing Down" an Existing Drum Track and Aif File.

I have an Existing Drum Track that plays fine in terms of volume. I imported song aif file that also plays fine in terms of volume. When I created a new Audio Track to record both together it's very quiet because it's recording it through the external mic.

Isn't there a way to "bounce down" to get an "internal" recording of both tracks that is at a normal level?

Cheers.