a Mix with 24 channels and proper gain staging runs at approximately around -10 db on the inputs of my AD converters ( Avid Omni set to +4db ).
-10dB what ? FS? is that peak or RMS ?
If RMS it's hot enough I suppose, if peak you have nice headroom but I wouldn't say too low either.
You'll need to check your studio(console) line level alignment, as the dBu<=>dBfs relation of your converter
To me (but that's just my taste that may defer from other) the console/studio line level is set @ -10dBFS (which is also my 0 PPM, analog peak) and 0 VU is aligned 8 dB below that (-18dBFS), I have both meters at master out.
With "proper" mix, 0 VU and 0 PPM are more or less hitting the same spot around 0, theorically -10dBfs peak, but fast DAW digital peak meter can show/catch around -6dBfs, probably ISP meter will add 1 or 2dB to that.
If my -true peak- (digital) hit around -10dBfs at the 2TK back record on a particular song/production it's probably OK too, it's usually when things are already peak shaped...
All in one...I'm not sure you have an issue ?
Best
Zam