Am I wrong in saying that a mic is a mic (No better or worse quality) when plugged and recorded directly into the 7D? I used the H4n and the Rode Stereo Video mic with the deadcat to capture the audio in the video below. In a very quick test at home I found the Rode mic attached to the H4n was able to cut out some of the noise (Hiss) in the audio that the mics on the H4n would capture.

A noob mistake perhaps? Thinking that a better mic attached to the 7D (Or 5D for that matter) would be that much better than the onboard mic?

I Feel Pretty - Chigusa on Vimeo

Its the pre amps on the 7d. try a decent xlr adaptor, Juicedlink models have about the best pre amps out there. It would also allow you to use 2 mics at the same time, ie shotgun and radio, and give you level control on both. They have just released an add on for DSLRs. http://www.juicedlink.com/index_files/CX_camcorder_XLR_microphone_adapter_audio_mixers.htm

It's not clear what you're asking. The onboard audio of the 7D is lousy. Using a good mic directly plugged in to the 7D will improve your audio. Using a dedicated recorder like the Zoom will improve your audio. Using an external preamp like the Juiced link will improve your audio.

Jason, the hiss is from the AGC (auto gain circuitry) that presently cannot be defeated. Colin's link to the DN101 attempts to defeat the auto gain by blasting a steady signal through one of the inputs on a Juiced Link. It will also limit you to a single mono channel, since the other channel contains the defeat signal.

For the combo price of a Juicelink mixer AND the DN101 defeat-er, you could buy a separate field recorder like a Zoom h4n or a Tascam DR-100. Double-system sound can be a pain in production and post-production, but will always give better quality and flexibility over any on-camera solution.

HTH,
Brian Brown