Did the D800 go into limiting or into protect mode?
The gain & master pots on the D800 are the type where you get the use of the whole range of the knobs.
You can't compare positions of the knobs between two different designed amps & say what it sounds to me like your saying.
I apologize if I'm misinterpreting what you're saying.
audio taper vs. linear taper pots. i'm pretty sure aged horse said they D800 uses a pot that allows it to continue to get louder past noon, while many other amps tend to max out near noon. of course, the trade off is that you may find yourself "cranking" the D800 so the master looks like it is at a higher setting. the reality is that each amp will sound almost identical at all down or all up. it is the middle range that looks different.