Wheresthedug had a genius idea, in another thread, that appears to be relevant to my issue.
I just did another test. I loaded the profiles mentioned before and disabled Stomps, Stack, and Effects. Plexi Drive is getting to -5 dB in my DAW.
68 Mars 50 1 8R is getting to -13.5. Huge difference. Rig volume is 12 o'clock on both.