Well when I first started reading I was about to say "Ahh... he's got a bad mic cable," but by the time I got to the end of your post, obviously that was not the case.
Barring any weird or funky settings (and it doesn't
sound like you have any), my first guess would be that you have a bad mic pre-amp in the camera.
A few things to ask yourself (and check) to help with the diagnosis...
Is the hiss
always there?... or sometimes it is, and sometimes it isn't? Sounds like before you might have been using the onboard (front) mic... was there no hiss there?
Is the hiss in
both left and right channels?... or just one of them?
Does the hiss vary in intensity when you turn the mic gain up and down? Or is it
always there at the same level, even when you have that channel turned down to zero?
Is it, and its level, affected at
all by switching the phantom power on or off?
Is it, and its level, affected at
all by switching the input type from mic to line in?
Knowing those things might help a bit...
T2
__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com