Preamp break-in

It's claimed an Ayre KX-5 Twenty requires a long, e.g. 500 hour, break-in to begin sounding its best.  Can it be that each input requires that break-in?

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Disclaimer:  Ayre Fanboy.

I think Mr. Hansen attributes the break in time to the ultra-fancy PCB material if that's the case, I would bet that the traces associated with each input require burn in while common components will burn in regardless of the input.