Burn in is not a thing in anything solid state.

I can somewhat believe that there is a burn in period for stuff that moves and needs to be loosened up a bit. I can even buy that certain amps that need to be operated at certain temp (tubes and class A) may need a few warm-up cycles to settle in. But nothing solid state should have any burn in period.

Why not just go to a carpenter and make a custom one that fits you?