What makes you build a system around an amplifier?

I bought a Pass amp and knew I could never give it up.

+1, @wolf_garcia 

That’s exactly how I felt when I first heard ARC VT-80 amp. Six months later, my rest of the system is now ‘tuned’ to extract every last bit of its goodness. The amp’s tonal purity, full bodied mid base, dimension and texture, all of which manages to relax me after a long day at work. 

So @wolf_garcia  and @jaybe  :

Can you be a little more specific? :) What SET do you put in this category? Jaybe, which Pass amp?

My system is built around my speakers which is the way it should be.

I don't get the concept of building 'around' a specific component..

We all have some sort of starting system that usually is assembled by a combination of what we can afford at the time, what advice we get from friends and magazines and what we happen across in the local marketplace.

After that we upgrade, sometimes haphazardly, sometimes because a piece of equipment we covet shows up at the right price, or because something in the system breaks down and needs replacing.  I don't have any audiophile friends that scrapped their whole system and started anew.

Sometimes one perceives that the front end needs an update, sometimes the speakers and sometimes the amplification - there is no rule nor commonest route, at least that I have noticed.

I don't even remember what order I upgraded in over the years, but I have equipment that has been in one or another of my systems since the late 1980s as well as systems with new (to me) speakers and amplification, but front ends that have been with me for some years.

I guess that I have to disagree with your premise - that people more often upgrade in any one manner.