When I said "amp" I meant what I read... they were referring to typical tube amps. I read that changes in voltages coming from the outlet could cause inconsistent tone. I totally get the Axe is consistent, day to day, but could other circumstances, like the voltage thing, contribute to it sounding differently.
I disagree about your explanation about the strings. It feels like the gain is getting dialled back, big time, so it "feels" harder to play. Obviously, the guitar isn't changing but that doesn't mean that things don't feel different.