I played around with my sytem quite a bit.. granted not all of it was sophisticated or double blind, just open minded observations.
I hooked up 2 channel with my Elite 94, vs my standard setup using my Sunfire Amp, and also had dug out my old Adcom 555II 200x2.
There wasn't a great deal of difference that I could detect or that would make me say once was very much better or even different, but I will say that I noticed "some" difference... most of which is very hard to quantify. I'd say the Adcom was a bit brighter, more in your face sounding. I noticed it on tracks that had a lot of treble sound like cymbals. I would say that the Sunfire was more laid back, less fatiguing. I think it just sounds a bit more fluid or liquid-y. The amps from the Elite sounded very much like the Adcom, but seemed to give up just a little bit of detail at very high volumes... again I noticed it in the trebel when cymbals played. You didn't hear as distinct a sound... more like continuous whoosh of sound as opposed to a distinct crisp crack of continued sound. This was extremely subtle and only on certain parts of music when I was really paying attention when I thought I may have heard a difference. Taking into consideration the time it took to right away swap to the wires to something else and re-listen, it's hard for me to say for sure.
These are all very subjective comments and I chose words that make sense in my head to describe what felt I was hearing. I really can't say that I would be unhappy or happier with either configuration. It all sounded very good to me and I was very pleased no matter what I hooked up, so take it for it's worth.
Again, this is just an opinon, but I think people sometimes mistake a "good sounding" amp for what it is because compared to more budget based power, amps or amp sections in higher end equipment may not have the muddied signal pat that budget based stuff may have. My thought is that the higher end you go, it becomes very difficult to hear differences because they're all so clean and unadulterated in what they do. I read professional reviewers discussing nuances between $10k amps. They're a lot better than me. In my limited experience of having higher end stuff to sit and listen to, I'm just not able to tell the difference or detect nuance like that.
So there you have my 2 cents based on my own equipment. After 3 paragraphs, I don't think I ended up saying much or coming to any conclusion or even answered you question, but I hope it helps in some way.