I keep talking about the manual audio levels being a big plus for the Canon 60D right now, and I think some people are still wondering what the big deal is. Currently only the 5D Mark II has this option and hopefully there will be new firmware for the other cameras. The in camera audio for the Canon 7D and T2i use AGC - automatic gain control that can't be disabled. The camera boosts the microphone signal pretty high that it has a constant hissing noise. If you're in a loud busy environment, you won't really notice this due to all the distracting sounds, but put these cameras into a quiet environment and you'll notice the difference big time. If you think Magic Lantern will be your solution, check out the comment I left in this article: https://cheesycam.com/canon-7d-vs-60d-vs-550d-t2i/
The workaround right now for cameras with AGC on all the time, is to use a separate audio recorder and record directly to that. Next you'll sync that audio in post. For shooting in 24p that gets a little tricky getting long audio to sync. For anyone shooting hundreds of short clips throughout the day, that also adds post processing hours trying to match everything up. If you want to shave some time on recording to a separate device, you can use devices like the JuicedLink DT454 or similar that will send a constant tone to one channel of the audio tricking the AGC. I have to say though that these Audiophile guys who build these preamp boxes weren't very happy with the Nikon DSLR's. Nikon have a different way of setting the audio and still didn't produce as nice results as the Canon's. Don't quote 'me' on that, but that's the scoop I got. We'll just have to wait and see if that's been improved on the newer Nikon DSLR's.
If you've got a few minutes to spare, great tutorials about AGC and the hissing noise can be found here: https://www.juicedlink.com/reducing-camera-hiss/chapter/0
Here's a very old example of a test I did when Magic Lantern was first released for the Canon 5D Mark II to allow manual audio levels. This should give you a better idea of what the new Manual Audio Levels in the Canon 60D are capable of. Not the best of the best, but much better quality can be captured if your camera allows you to manually set the amount of gain.