I don't disagree with Goraman's comments about amps and other switching around not making more than minor differences, compared to what changing speakers offers in the equation. However, I would say that sometimes for me that 1% difference is all the difference in the world. That's really what I'm playing around with in my amplifier switching. I had a Decware Torii II over last summer for a weeklong trial, and I didn't get near the magic from that tube amp with my Lores than I'm getting with the SP3 right now. Slightly different flavors of the same base sound for me. The Ampino was my preference in the Decware shoot-out, but so far this SP3 is giving almost all of the strengths of the Ampino with some additional soundstage and tonal body to instruments.
Are they completely different animals? No. Do they give slightly different, but definitely distinctive lenses on the basic qualities of the Lores? Yes.
Granted, neither of these amps are what you would consider true high performance amps. They're both awesome for the money, and that's the level of money I can play with. I assume stepping up the ladder would lead to greater refinement, and right now I'm trying to decide which ladder to step up.
So, I guess I'd say that while I'm still experimenting, I have found in some of my trials that 1% is sometimes all you need to make the difference between good/interesting and truly involving.