Why do components sound different?

It's a pretty simple concept. All equipment has it's own sound signature. Period. If it didn't we would all have cheap ass mass market junk and be happy. 

No audio equipment is totally transparent to the source.

He's an engineer who thinks he knows better and will enlighten us. 

We'll see if he humbles himself and learns over time.  :) 

I think you don't understand HiFi.  :(

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Who would that be oh wise one? Remember just because you have an opinion doesn't mean it has any weight with a guy like me. YOUR understanding of HiFi is surely your own. I don't share a LOT of your views on equipment or testing, so opinions do vary, ay?

I KNOW all equipment has it's own signature and that can change with just the AC power source. The second is always the room size and treatment. Equipment/electrical 50%, room set up, and speaker placement 50%.

I been working on two systems off and on for 15 years. One (Elixirs) that 
has taken a lot of time to change the design without messing up the original cabinet design to much.. Making your own system work for you is tough, especially when you have bouts of OCD like me.. I like heavy equipment racks and heavy speakers cabinets and have an OLD back.. LOL.

Neutral, what's neutral, in neutral and coasting? There is no such thing as neutral. It's like calling something pinkish, 50 shades of pink...

NOW it time to throw the hat on the floor, and get ready for the weekend.
Yes my friend, turn up the music, as I slowly walk around the hat to the beat of the music and my faithful dog follows me. I STOP. I stomp my feet (both) and back around the hat very slowly as the dog shakes the toy and the stuffing flies out.. OLAY..

Time to feed the chickens..

Regards

OP said:
"The perfect component would have a linear frequency response, no distortion ( no harmonics which are overtones of the original signal) and introduce no other frequencies."

But none of them are perfect ant THAT'S why they all sound different!
GET IT?