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

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.

here here

why did manufacturers used to make power cords that were hardwired, and millions of music nuts didn't give a ratsass about burn-in? jeez were we simple?..or simply happy with the equipment? UL approved red cords always sound better than UL approved black ones, and blues ones always trump the red. throw in the words 'hospital' or 'military' and your electricity will really pay attention.

I listened to my system for a year with the stock power cord.
I decided to try a new cord and it did make a difference.
A window in my room began vibrating/rattling.
Never did before.
Some frequency was boosted and made that glass vibrate.

We do 90% of the burn-in here in our shop. The last 10% takes the longest time- up to 6-8 weeks depending on the number of hours a day. Especially when you have amps or preamps built up with custom options, doing an extended burn-in is just plain impractical!

As to power cords, we acknowledge that power cords are going to make a difference. That is why we install IEC connectors on our products. The problem is, what we think is the best power cord may not be what you think is the best power cord. In fact we have seen a power cord work great in one installation and make no difference in another. You have to take into account that variables of house wiring, cleanliness of the AC power, neighborhood line voltage and other system anomalies that will affect what the end user thinks is the 'best'.

Guess what? No-one can do predict all that- so that is why we supply our gear with IEC connectors. Our stuff is known for being really transparent- and we invite you to experiment. That is the only way I know of to sort out what is going to work in the area of power cords. It would be frustrating as an end user to realize that a $200 power cord had been included with the unit, only to find out that in your system its not the right combination!