Note that firewire carries

Note that firewire carries audio and video. Its up to you to exclude it out in the timeline of your NLE unless you choose not to capture audio in your settings.

Audio from your mixer can go into your Mac a number of ways

1. The audio In port on your Mac accommodates both optical digital audio input and analog audio input.
using a 3.5mm mini phone jack from your mixer output

2. Using a USB audio interface for your mixer (Like Edirol’s UA-1EX)

3. Record the sound as a separate file and drop in your timeline.