So, my normal setup for camera audio is a Sennheiser ME66 on the camera (using the camera's phantom power) and a wireless lav. I shoot with no attenuation or limiter (I'm using a Canon FX100) and have not had any audio issues when the levels were good.
Plugged an Audio-Technica AT2020 directly in, with phantom power on - and even though the levels are peaking between -20 & -10, there is distortion in the recording.
Attenuation "fixed" the distortion, but why would I get distortion from one condenser mic - plugged directly into the camera - but not the other?
As another test, I tried running the AT2020 through my Zoom F4 (turning off phantom in the camera). Again, the F4 levels were fine and the recording was clean - but there was distortion in the camera's recording, even though the input never got above -20. Again, attenuation took care of this.
It's almost like there's some kind of uncontrollable pre-amp in the camera or something...but why wouldn't it fry ALL the signals coming in equally?