If you work with sound, your ears are trained.
I bought a set of Logitech 2.1 speakers with sub a few years ago for my computer. I was pretty happy (still am for the price) with them. Now, as my job has me working with some amazing musicians, an awesome Digidesign VENUE D-show mixing console, and impressive stacks, well, now I want more out of my speakers.
I'm no expert, but my ears sure hear things differently than they did a year ago.