Here is something I found quite amuzing:
From the French Audio Magazine on a Bryston amp.
When you get it fresh from the factory, this amp is, for all intents and purposes, unlistenable. It requires at least a two-week break-in period before it shows its real stuff I was able to hear it both before and after its two- to three- week high volume workout: the difference is colossal! Of course my real test was done with a system that was well "broken in" and that was connected to a high-quality source and first-class speakers."
From the 10audio review on Bryston amp:
"If there was a break-in period, it was probably less than 10 hours. I used the amp for background music for a day before attempting any serious listening, and was not aware of a change in the character of the amp afterwards. Ive remarked in other reviews that almost every component sounds pretty bad for the first 10 hours or so. That observation probably does not apply here due to the extensive run-in every Bryston product receives at the factory before shipment. Dont you wish that every other maker of high-end electronics would deliver a product that you could actually use as intended upon receipt?"
So what we have here is one guy who finds a "collosal" difference after 3 weeks and another who finds nothing after 10 hours.
The truth is Bryston "burns in" their amps at the factory extensively for over 100 hours in order to make sure they are stable, meet the specs and so they can give you their 20 year warranty!!!