I think tone is in the ears. I am an at home only player with all my gear in one room all the time. Yesterday, I got in two hours of blissful playing. To the extent of my limited ability, everything sounded just right. When I returned a couple of hours later to reclaim the feeling, everything was just wrong. Same gear, same location, same settings, but a vastly different experience.
This is a very common experience for me: same gear, same settings, same controlled environment, but different results.
Well, I think we're saying the same thing, in different ways. The ears are only the brain's transducers, the brain still has to process the sounds the ears hear in order to understand them.
But the brain, the ears, and the hands are all operated via the body's chemistry, and the chemistry of the body changes from day to day and from hour to hour. It's different after a big meal than it is first thing in the morning, for example. The brain, in particular, depends heavily on glucose for its operation. If you were to take your blood sugar at different times of the day, it'll vary.
As a diabetic, I have experienced the effect of taking too much insulin and depriving my brain of glucose. The first things that shut down are one's peripheral vision and the sense of hearing changes. Yet the hearing and vision organs are transmitting the same information to the brain as when this hypoglycemic condition isn't happening. What's different is that the brain, short of the chemical glucose it needs to operate, cannot process all of the information. This is an extreme example of what happens, but it's an example of how the brain depends on the chemical processing of food in the body.
This is one reason why a person's perception of sound, and ability to produce sound, can vary at different times. It's processing information differently as your internal chemistry goes up and down during the day.
And when you're tired, your body is processing things differently, too.
The environment can be controlled, the difference is what's going on chemically and the brain's reaction to what it's hearing. The sound might be the same. The brain's perception, however, is the variable.