There is no benchmark, it varies by component. In detail, what I have personally experienced is a very wide break-in period variance with no empirical explanation other than an anecdotal summation that the better the build quality, the longer the break-in period. Again, this is only my personal observation .... your experiences may indeed be substantially different.
For example,
(1) My HT electronics (Bluray spinner, AV kit, ~ $6000) break-in period took about ~ 100 hours +/- break-in time, with arguably and ill-defined nominal changes after that initial break-in period.
(2) In contrast, my 2-channel "A" system electronics (digital source and integrated amp ~$25, 000) with a much higher build quality and resulting pricepoint strata, took at least near- 400 hours initial break-in time to reach a certain plateau where any further changes curves now flattened out.
There were some more subtle further slower evolution changes over the next few hundred hours of use.
Note: The break-in period audio performance improvement curve was not a pure straight-line linear one , but rather a series of incremental non-predictable ad-hoc steps.
Without prejudice to any the above , the new audio performance that appears "warmer", and "cleaner" as you highlighted , may actually be a result of the following rather than any enhanced break-in period:
(a) it has a markedly different sonic signature of the new gear brand itself, that you personally (emphasis added) prefer, in conjunction with
(b) a more pleasing audio performance in your bespoke system ( again, emphasis added...) provided by a a "better" system synergy now overall.
For example,
(1) My HT electronics (Bluray spinner, AV kit, ~ $6000) break-in period took about ~ 100 hours +/- break-in time, with arguably and ill-defined nominal changes after that initial break-in period.
(2) In contrast, my 2-channel "A" system electronics (digital source and integrated amp ~$25, 000) with a much higher build quality and resulting pricepoint strata, took at least near- 400 hours initial break-in time to reach a certain plateau where any further changes curves now flattened out.
There were some more subtle further slower evolution changes over the next few hundred hours of use.
Note: The break-in period audio performance improvement curve was not a pure straight-line linear one , but rather a series of incremental non-predictable ad-hoc steps.
Without prejudice to any the above , the new audio performance that appears "warmer", and "cleaner" as you highlighted , may actually be a result of the following rather than any enhanced break-in period:
(a) it has a markedly different sonic signature of the new gear brand itself, that you personally (emphasis added) prefer, in conjunction with
(b) a more pleasing audio performance in your bespoke system ( again, emphasis added...) provided by a a "better" system synergy now overall.