Hi Amber, The problem with the 7D ws that it adjusted the audio gain automatically. If you were filming a scene and there was no or little noise then the camera would increse the sensitivity of the audio in an attempt “to hear something” which induced a hiss. now that we have manual level adjustmen you can turn the gain down to a level where there is no hiss and life is good again! Good audio is important in any video, if you have an sound level that is continually going up and down then it will very soon become an anoyance. so, turn the levels down so that they only “peak” very seldomly and leave it at that. I hope that this is of some help.
Cheers
Niall
