How much does volume matter when breaking in amps and cables?

Why would you need to “break in” electronics?  There are no moving parts.  Speakers, yes:  electronics?  I never heard of that!  This is not something you can actually hear---or even measure.

If I hooked up an amp that was broken in to an identical set of speakers and one thst was broken in,  you couldn’t tell the difference.  Heck, at the same volume levels, no one can tell the difference between amps at all.  

Warm up?  That I can understand.  I leave my electrical equipment on all the time since tolerances change as the temperature does.

The quality of the sound is dependent on how much you paid.  If you take two bottles of wine, one costing $100 and one costing $20, and change the labels, almost everyone will tell you that the new $100 bottle is way superior to the old $100 bottle.  

Explain to me what is changing in electrical equipment “break in”, other than temperature.