The only things in my experience that change their sound in the first
few days of operation are loudspeakers. (And then not by much).


It may come as a surprise to a few here, but the minute you start to use
*anything* in this world it's 'physical characteristics' start to
change and it starts to wear out....

Agreed. However if you then look at the actual details you may find that
in
some cases the rate of change is quite small... :-)

Also 'wear' would not explain why a unit is alleged to require a fresh
warm
up for each new use after it has been left unused/unpowered for some time.
Hence my understanding is that people are not describing 'wear', but a
change that undoes itself with lack of use and has to be redone when use
recommences.

Such as when components selected in the design (for whatever reason) are
such as to perform at their optimum when they increase in temperature?