Equipment Break-in: Fact or Fiction

I'm with Marakanetz on this one. I believe that your brain is doing the majority of the burn-in, except with speakers.

rbnl ... are you sure that Boeing's burn in doesn't relate to safety ... that is, electrical equipment is most likely to fail during the first few hundred hours. All manufacturers of safety-critical electronics perform such burn-in to prevent failures in the field.
Or perhaps there is self-calibrating software in their equipment ? This is also quite likely.
Either way I think that aircraft electronics and a simple transistor amplifier (or CD player) are rather incomparable.
Not to say it doesn't exist in audio, but I don't find your argument persuasive.

Ok, since many of the "believers" seem to want to lambast us skeptics here is my reason for being skeptical, or at least attributing the bulk of the effect to the brain of the listener.
I have two systems, one in England (now in my parents' living room) one in the US where I have been "temporarily" living for 5 years. When I visit the UK, roughly every 18 months, for the first day or two my old system sounds bass heavy and lacking in detail. After a few days it sounds thoroughly enjoyable. When I return to the US my US system sounds detailed, but lacking in rhythm. After a few days my US system sounds very enjoyable.
Both systems cost about $3k, and a mix of new and used. I believe both are at comparable performance levels, and both represent pretty much the pinnacle of a $3k system. However both have different strengths and weaknesses. The US system excels at chamber music and light jazz. The UK system excels at rock, particularly live rock, but handles classical very well.
I believe that over a period of time, measuring days, my brain becomes attuned to a particular tonal balance. Since both systems don't contain a single component less than 5 years old (some are >10 yrs) burn in is not possible. Both are left permanently switched on.
Since I'm an open-minded EE I'm prepared to accept that there might be minor changes in sound over time due to many different second-order effects. However I also believe that these changes are swamped by the adjustment of ones brain to a new tonal balance, based on the experience I have just outlined above.
I also believe that to strive for the "perfect system" is something of a wild-goose chase, since I have found that I can live very happily with many different systems, provided that I have time to attune to their particular sound, and provided that they are reasonably good systems to begin with.
Hey, don't flame me ... I offer a sincere opinion, with evidence upon which it is based !

Redkiwi .. here here! Some think burn-in is in one's head. Others think it's in the equipment. Neither side appears to have presented conclusive evidence (electrical measurements, or psychoacoustical studies), so lets all be happy to differ. So long as we're all pleased with the end result.

Drubin .. sometimes changing cables can improve the connection. A connection left in place for a long time can be prone to oxidation and dirt. I have had this experience once or twice when my system has had to be moved after several years of no changes. Also cleaning terminals with contact cleaner and replacing cables can have a profound effect.

Thanks Twl. Perhaps my system or ears are not sufficiently sensitive to hear difference ... I fully accept that this is a possibility.

You know, there's one post above that raises a question that has been on my mind regarding this issue .... "why does everyone report the sound improving during break-in ?" If break-in is a purely electrical phenomenon then wouldn't we have a good proportion of components sound worse after break-in ? However, if the effect is in large part psychological then this would go some way to explain why everything sounds better after break in since our brains are wonderfully adaptable to new experiences.

Now I'm not posting this to provoke the "believers", rather because I think it was a very interesting point.