This is the video setup I have:
For those unfamiliar, the Zoom H4n is a field recorder not an external mic. Under normal use, you need to slate the audio and then sync it in post processing.
I have connected the H4n directly to the 7D via the headphone out. This way I avoid having to sync the audio later. With this setup, I have the option of treating the H4n as an external mic, or if audio quality is important or I'm required to be far from the sound source, I can also place the H4n next to the sound source and sync later.
I have a connection to my iPhone emitting a 20Hz tone because magic lantern isn't available yet for the 7D. The 20Hz tone will suppress the AGC but the frequency is low enough that it is not audible (unless you have amazing hearing).
Questions?