Same equipment, including source, cabling, conditioning, speakers, room, etc. Change amp and listen again. That is really the only true way to make a determination of this sort. A/B comparison with changing only one thing.
Otherwise, the difference in sound could be attributable to any number of things that were changed. no way to get around that.
In WC's case, he has not only changed amps, he has changed, pre-amps, cables, speakers, etc. It would probably be physically impossible for him to change only one thing. So, we are taking his impressions on the move as life goes on.
I have no problem with that.
My issue (if it really is one) is that most of the equipment he has tried has actually been quite nice. So, I would be very careful saying that something is bad. It just may not have worked well in that particular setup with some of the equipment used at that time.
Pass labs makes outstanding equipment. period.
With the system WC has now as his "reference". Amps, speakers, cables, source, pre-amp. If he were to go back (I know it is impossible, so don't kill me here) and re-evaluate the pieces he has tried previously, only replacing that one piece, I can believe that he would hear differences. But keeping within price points on equipment, I can say that I don't think there will be jaw dropping differences between equipment in the same price point category.
Like I said earlier. For example, Parasound make quite decent equipment. Place them with Martin Logan Neolith speakers and they will sound quite nice. If they didn't it may be because of many reasons. 1) room, 2) cables, 3) power condition, 4) terrible music (have experienced this at shows), 4) any number of things.
I am appreciating WC's journey through the "high-end" audio world. It is quite fascinating. But, people should take this with a grain of salt. It is quite fun, but, other than taking someone's word for it, what is the best ways to judge equipment?
1) take it home and place that piece in your system, changing only that piece, match levels and listen. Do A/B vs the original piece and have fun.
2) go to a friend's house and listen to his/her system with that particular piece and judge. Understanding that if you buy that piece and take it home, most times it will perform quite differently in your system than in your friends.
3) go to shows and hear a piece in the set-up presented at the show. With the understanding that Number 2 above will also apply.
WC is giving (in my opinion) an honest view of how certain pieces sound in his system. I like that. But, I do understand and acknowledge that along the way, he has changed many things. So, direct comparisons were not possible in some cases. in others, like now, there can be direct A/B comparisons.
So, my point (finally) is that I wouldn't be so quick to say that previous equipment tested was inferior or bad or lacking. It was and is an evolutionary process, not direct A/B comparisons. so memory plays into this in a very real way. But, that memory has to also consider that it was more than one piece, or room, that changed.
Still great fun and I'm enjoying this greatly.
Tell you what I would really like now.
Audio Research REF 10 pre amp vs Atmosphere top of the line pre, vs CAT, etc. Changing only the pre-amp. I know, hard to do, but wouldn't that be fun also?