Bean - in Audition, click on VIEW > Multitrack View. drag the DAUD source to Track 1 and the DSBD source to Track 2. sync them up.
then, on the left side of track 01, you can adjust the volume with the vertical dB slider (if the vertical slider is not showing, then Right-click on the part in Track 1 that says "V 0" and the vertical slider will appear)... drag it down to around - 6 dB, and listen. adjust that dB slider as necessary until it sounds good, then click on EDIT > MIX DOWN TO FILE > ALL AUDIO CLIPS. then Audition will create the new WAV file (mixed from both sources).
that should set you up nicely.