Why manufactures don´t burn in their amps and ...

Burn in, for either audio gear or cars, is not performed at the factory (other than rare exceptions) for the simple reasons of cost and practicality. Would you want your "new" car to arrive with 2,000 miles on it just so you could run it flat out on day one? Both audio gear and cars were originally (and still are) set up to be displayed, demo'ed and sold by a dealer. The dealer's gear is assumed to be already run in so the buyer can get a feel for the end product during the demo. I believe that 50 to 100 hours is plenty of burn in for audio gear to achieve its characteristic sonic signature. It may continue to improve over time, but after 100 hours you should be hearing much of what you purchased.

Manufacturers do not include upgraded power cords for the same reasons they do not include stillpoints for support or other tweaks - first, including expensive extras will not allow them to achieve attractive price points, and second, the buyers who want something different will never agree on what "improved" power cords, footers, etc. are best.

Of course, if you buy your gear on Audiogon, it will come already burned in, and you will have saved enough money to purchase an upgraded power cord.

Power cords? Burn in? Seating the Pistons? LOL, I love this stuff.

I can't tell you how many times I have seen a performance engine built and tested up to it's estimated RPM limits as soon as it's ready with fluids and exhaust. Never, and I repeat NEVER does anyone talk about a break in period. That's a myth propegated by the manufacturers to help people justify thier expensive purchase. If you buy an M5 BMW you can floor it right off of the dock in Newark, Houston, or Long Beach, it will be just fine, your friends in Bavaria built it that way. Same goes for your Nissan, Caddilac, Corvette, or Porche.

BTW, we have built 550 - 900 HP engines, tested and tuned them at extreamly high RPM's, then dropped them right into the cars to race (strip and road) without any problems at all. No break in required. Most were the same blocks and components that come with your car from the manufacturer just modified with some performance parts, so these are not crazy one of a kind engines.

Watch Horsepower on SpikeTV on the weekends to get an idea of the myth of engine breakin. They start at 5000 rpm runs, and go up after about 30 seconds, that's the breakin.

IF burn in were required, just think of the facility required.
1 station with good power for each amp along with dummy loads appropriate to the power. One good power glitch and there goes a couple months of inventory....poof!
The heat alone would put a dent in ANY electric bill. Unless of course you did all your burn-in during the winter!
Bryston does so simply for infant mortality reasons and in order to provide for the #1 industry warranty.
Also, I have read some posts where people periodically re-burn cables!!
No mention is made of the other half of the equation....that your ear/brain gets accustomed to the sound it hears.

This I believe: components don't burn in; listeners burn in. "Burn in" is a metaphorical cousin of "break-in": baseball gloves require breaking in; conert grands--specifically, the action-- require breaking in. The wood in string instruments changes. We love to think of things breaking-in, balancing, aging into maturity and ripeness. We like to think of metal components, non-organic and w/ no moving parts (excluding drivers), doing the same. Isn't it odd, though, that "burning-in" is supposed to result in better sound? Isnt' that very congenial on the metal's part? Why should that be? We imagine things "limbering up," "getting settled." Just as I like to imagine that my tube amps give me a warmer, more open sound. I suspect that I'm transforming the literal warmth--the visible glow--of the tubes, and the delightful, illuminated open space inside the glass globes themselves, into my perception of the sound. Solid state. I mean who wants to hear music from something called Solid State. Definitely not open, and not warm and glowy.

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