A moment when you realized better sound was possible.

I have external crossovers. I read on a forum (maybe this one) about how solid core wire sounds different than stranded. I went to the hardware store and grabbed some 20 gauge solid core doorbell wire and ran that between the crossover and the tweeters. This was eye opening for me because it proved to me that cables do in fact matter. 
Two more experiences further opened my mind: upgraded interconnects and a power cable for my amplifier. I began to realize that virtually every piece of the chain is in a sense a component, which sent me on a mission to tweak every last piece of my system to get the best sound possible out of it.

I began to realize that virtually every piece of the chain is in a sense a component, which sent me on a mission to tweak every last piece of my system to get the best sound possible out of it.

"Virtually". Good one.

I began to realize that every piece of the chain is indeed a component, which sent me on a mission to tweak every last piece of my system to get the best sound possible out of it.

FIFY.

Hi,
age 13 and i had a mono Philips record changer with ceramic cartridge and a full range speaker having the magnet infront. I did not even know what stereo was so i thought just adding a speaker would upgrade it to stereo. NO, but i clearly understood that the new speaker was no match  compared to system's original. A year later i heard my first stereo system playing Child in time from Deep Purple, that was it, but it took me 1 more year to buy my first real stero (at the store i listened only to the speakers with the amp), Wharfedale Lintons, Kenwood amp, Lenco tt. So i could hear speaker differences, cartridge differences (i changed 3 on that Lenco) and if an amp had good drive or not. The biggest step though happened, back in the 80's, and with no return, when i bought secondhand a Mission 775SM with 774 tone arm, a new then Cyrus 2/PSX (plastic cover) driving a new TDL Studio 2 speaker. A Pink Triangle with Alphason HR100S and ARC SP-9MKII in the early 90's sealed it. 

In the very early days of CDs I definitely heard some problems with them, although I was instantly enamored with the lack of pops, scratches, wow and flutter, and background hiss. One thing I could hear was a hissing around flutes that I didn't hear on LPs. This was later, I believe, recognized as problem with early CD players. There was also a buzzing sound in one of my Telarc CDs. Chariots of Fire lacked the atmosphere I percieved on the LP. I'm not sure if that was a change in the mixing or an effect of the CD players back then. I haven't heard that LP or CD in ages now.  By the year 2000 I no longer preferred LP. I still have the recordings where I originally heard the hissing flutes and the other one with the buzzing. Both effects have been long gone for years now even on the cheapest DVD players. It's fabulous to me that after countless playings both of these CDs are no worse for wear.