Why does it take so many hours to brea in arc preamps and amps?


I recently purchased a like new ARC 5 SE pre amp.  The unit had less than 200 hours on it.  Everything I have read states that ARC preamps take up to 600 hours to fully break in.  Why is this so and what improvements can I expect to hear as the unit accrues hours?
ewah
the only breakin time I worry about is with new speakers

I do think ARC tells you to warm their components up a bit for best sound, but it won't kill you to listen to an ARC pre-amp that isn't all the way warmed up


at least, it won't kill you right away
"Let’s play with the "burn in" crews heads.

If you think about it, all the optimum adjustments are made at the factory after the amps been on for a while, maybe an hr if your lucky.
If thing change after 600hrs then those optimum factory adjustments have just gone out the window and need to be redone again.

So it’s either out of adjustment because of aging, and therefore not optimum, or the factory needs to have them on for 600hrs before they are adjusted and sent out to the shops.
Either way if things change they would be out of the original optimum adjustment.

Cheers George"

I understand what you're trying to say here, but that's really not how it works. When a designer is building a new product and makes changes, the component gets broken in before they listen to it. For about 20 years now, I've been evaluating prototype's during the design phase for several manufacturers. I break in every piece of equipment they send me. Sometimes I'll see the same component 10-15 times as changes are made. That means I break it in 10-15 times.   
I've never heard anyone say that their component sounded worse after break in.  If break in is a real phenomenon, then statistically how is that possible?  Unless it explains why we constantly 'upgrade' to new gear.  What if gear only sounded good for 1-200 hours, and then it was all downhill from there.  Obviously, over very long periods of time component parts degrade and do need replacement.  But I would not call that part of "break in."
Most of my experience with break-in (as opposed to warm-up) is with speaker crossovers, and caps. Replacing a cap takes at least 24-72 hours for them to settle in and give you a "final" version of the sound.

I wish I understood the physics. :) I understand one hypothesis that is often stated as likely is placebo. I understand why it’s such a possible and easy answer but to me it’s not enough.

Like other things in Audio, it remains an area not fully explored. I hope someday there will be results that better explain what we perceive.

Best,

E