I've recorded dozens of audiobooks with these settings, and this is a first.
I create an audio file (in waveform mode), and start recording.
All interface and mic settings are the same as always, yet the waveform is limiting at -6 dB.
The sound will still clip audibly, if I raise my voice into the mic, but the meter doesn't show it clipping (it maxes out at -6 also), and as you can see in the attached screenshot, the waveform is limited at -6 dB.
Any ideas about where to start troubleshooting this?
Since Audition records faithfully anything it's sent from your sound device, I'd start with that. Can't tell you any more though, because we don't even know whether you're using a Mac or a PC...