I couldn’t find anything about this in the manual. Does anyone have a sense of how much internal headroom is available? I was overdubbing some vocals and wanted to hear a specific track much louder than normal. So I pushed that track’s fader way up and it was regularly hitting 10dB or more above zero. But it never sounded like it was distorting. Now it was routed to a group channel set fairly low and was kept under 0dB at that point and at my audio outs. This suggests that there is a fair amount of headroom available internal to Cubase. I curious as to how much.
At least 12 db or 6 db, which you can set in project setup.
On top of that, you can add gain in the channel strip. Cubase seems to have a huge amount of headroom, and I could not tell you exactly what that number might be.
Roughly 1500 dB if your signal path is completely in 32 bit FP.
Wow, math skills to the rescue. That’s huge 
Gain structure and headroom isn’t issue with any modern (floating-point) DAW. As Thinkingcap said, you have far more headroom you can ever even think to need.
Only places where gain matters are:
- Inputs: Your A/D converter is not FP and even if it was, it’s headroom would be limited by it’s analog part.
- Outputs: Your D/A has same limitations as A/D.
- Recording/exporting to the file: If you are not using floating-point files you are limited to signal levels below 0dBFS.
- Some plugins:
4 a. Compressors doesn’t usually have threshold setting above 0dBFS
4 b. Some plugins (mainly analog gear emulations) have a “sweet spot”
4 c. Some plugins may be coded incorrectly and/or not using floating-point processing